The biogenetic law applies just as much to the brain, the organ of

mind, as to any other organ of the human body. On the strength of the

ontogenetic facts, which fall under direct observation, we infer that

there was a corresponding development in the phylogenetic series of

our animal ancestors. A significant confirmation of this inference is

found in comparative anatomy. It shows that in all the skull-animals

(_craniota_)--from the fishes and amphibia up to the apes and man--the

brain is developed in the same way, as a vesicular distension of

the ectodermal medullary tube. This simple oval cerebral vesicle

first divides into three and afterwards five successive vesicles by

transverse constriction (_Anthropogeny_, chapter xxiv., plate 24). It

is the first of these vesicles, the cerebrum, that afterwards becomes

the chemical laboratory of the mind. In the lower craniota (fishes and

amphibia) the cerebrum remains very small and simple. It only reaches

a notably higher stage in the three chief classes of the vertebrates,

the amniotes. As these land-dwelling and air-breathing craniota have

more difficult work to do in the struggle for life than their lower

aquatic ancestors, we find much more varied and complex habits among

them. These hereditary habits are gradually converted into instincts by

functional adaptation and progressive heredity; and with the further

development of consciousness in the higher mammals we have at last

the appearance of reason. The gradual unfolding of the mental life is

accompanied step by step with the advance of its anatomic organ, the

phronema in the cortex. Recent careful investigations of the ontogeny

and histology of the origin of mind (by Flechsig, Hitzig, Edinger,

Ziehen, Oscar Vogt, etc.) have given us an interesting insight into the

mysterious processes of its phylogeny.

While the comparative anatomy of the cortex gives us a good idea

of the gradual historical development of the mind in the higher

classes of vertebrates, we get at the same time from their fossilized

remains positive indications as to the period of time in which this

phylogenesis has slowly taken place. The historical series in which the

classes of vertebrates have succeeded each other in the great periods

of the organic history of the earth is directly demonstrated by their

fossil remains--the real commemorative medals of natural creation--and

gives us a most valuable record of the ancestral history of our race

and of the mind. The oldest strata that contain vertebrate remains

form the huge Silurian System, which were, on the latest calculations,

formed more than a hundred million years ago. They contain a few fossil

fishes. In the succeeding Devonian System these are followed by the

dipneusta, transitional forms between the fishes and the amphibia. The

latter, the oldest four-footed and five-toed vertebrates, appear in

the Carboniferous Period. They are succeeded in the Permian, the next

system, by the oldest amniotes, the primitive reptiles (tocosauria).

It is not until the next period (the Triassic) that the oldest mammals

are found, small primitive monotremes (_pantotheria_), then marsupials

in the Jurassic, and the first placentals in the Cretaceans. The great

wealth of varied and highly organized forms which are contained in this

third and last sub-class of the mammals appear only in the succeeding

Tertiary Period. The numbers of well-preserved skulls which these

placentals have left behind in fossil form are particularly important,

because they give us an idea of the quantitative and qualitative

formation of the brain within the various orders; thus, for instance,

in the modern carnivora the brain is from two to four times, and in the

modern ungulates from six to eight times, as large (in proportion to

the size of the body) as in their earliest Tertiary ancestors. It is

also found that the cortex (the real organ of mind) has developed in

the Tertiary Period at the expense of the other parts of the brain. The

duration of this Cænozoic Period has lately been calculated at three

million years (according to other geologists twelve to fourteen or more

million years). It was, at all events, sufficient to make possible the

gradual development of the human mind from the lower intelligence of

our ape-ancestors and the instincts of the older placentalia.

We have given the physiological name of the "phronema," as the real

organ of mind or the instrument of reason, to that part of the cortex

on the normal anatomic condition of which the action of the human mind

depends. The remarkable investigations during the last few decades of

the finer texture of the grey cortex (or cortical substance of the

cerebrum) have shown that its structure--a real anatomic "wonder of

life"--represents the most perfect morphological product of plasm;

and its physiological function--mind--is the most perfect action of

a "dynamo-machine," the highest achievement that we know anywhere

in nature. Millions of psychic cells or neurona--each of them of an

extremely elaborate fibril molecular structure--are associated as

special thought-organs (phroneta) at certain parts of the cortex, and

these again are built up into a large harmonious system of wonderful

regularity and capacity. Each phronetal cell is a small chemical

laboratory, contributing its share to the unified central function of

the mind, the conscious action of reason. Scientists are still very far

from agreement as to the extent of the phronema in the cortex and its

delimitation from the neighboring sense-centres (sensoria). But they

are all agreed that there is such a central organ of mind, and that its

normal anatomic and chemical condition is the first requisite for the

life of the human mind. This belief--one of the foundations of monistic

psychology--is confirmed by the study of psychiatry.

The study of the diseased organism has greatly furthered our knowledge

of the normal frame. Diseases are so many physiological experiments

made by nature herself under special conditions, which experimental

physiology would often be unable to arrange artificially. The

thoughtful physician or pathologist can often obtain most important

knowledge of the function of organs by carefully observing them during

disease. This is especially true of diseases of the mind, which

always have their immediate foundation in an anatomical or chemical

modification of certain parts of the brain. Our advancing knowledge

of the localization of mental functions, or of their connection with

special phroneta or organs of thought, is for the most part based on

the experience that the destruction of the one is followed by the

extinction of the other. Modern psychiatry, the empirical science of

mental disease, has thus become an important element of our monistic

psychology. If Immanuel Kant had studied it and had visited the

asylum wards for a few months, he would certainly have escaped the

dualist errors of his philosophy. We may say the same of the modern

metaphysical psychologists who built up a mystic theory of an immortal

soul without knowing the anatomy, physiology, and pathology of the

brain.

The comparative anatomy, physiology, and pathology of the brain, in

concurrence with the results of ontogeny and phylogeny, have led

us to form the sound monistic principle that the human mind is a

function of the phronema, and that the neurona of the latter, or the

phronetal cells, are the real elementary organs of mental life. Hence

modern energism is perfectly justified in regarding mental energy

(in all its forms) from the same point of view as all other forms of

nervous energy, and in fact all manifestations of energy in organic

or inorganic nature. Fechner's psychophysics had already shown that a

part of this nervous energy is measurable and mathematically reducible

to the mechanical laws of physics (_Riddle_, chapter vi.) Ostwald

has, in his _Natural Philosophy_, lately emphasized the fact that all

the manifestations of mental life, not only sensation and will, but

even thought and consciousness, can be reduced to nervous energy.

Hence we may distinguish what are called mental forces from the other

expressions of nervous energy as _phronetic energy_. The monistic

research of Ostwald on the energy-processes in mental life (chapter

xviii.), consciousness (chapter xix.), and will (chapter xx.) is very

notable, and confirms the views I advanced in the second part of the

_Riddle_ (chapters vi., x., and xi.). Ostwald has, however, caused

some misunderstanding by insisting on substituting his idea of energy

for the pure notion of substance (as Spinoza had formulated it), and

by rejecting the other attribute of substance, matter. His supposed

"Refutation of Materialism" is a mere attack on windmills; his energism

(the consistent dynamism of Leibnitz, etc.) is just as one-sided as its

apparent opposite, the consistent materialism of Democritus, Holbach,

etc. The latter makes matter precede force; the former regards matter

as the product of force. Monism escapes the one-sidedness of both

systems, and, as hylozoism, refuses to separate the two attributes of

substance, space-filling matter and active energy. This applies to

mental life just as to any other natural process; our mental forces or

phronetic energies are just as much bound up with the neuroplasm, the

living plasm of the neurona in the cortex, as the mechanical energy

of our muscles is with the contractile myoplasm, the living muscular

substance.

In the exhaustive study of consciousness which I gave in the tenth

chapter of the _Riddle_ I sought to show that this enigmatic

function--the central mystery of psychology--is not a transcendental

problem, but a natural phenomenon, subject to the law of substance,

as much as any other psychic power. The child's consciousness only

develops long after its first year, and grows as gradually as any other

psychic function; like these, it is bound up with the normal anatomic

and chemical condition of its organs, the phroneta in the cortex.

Consciousness develops originally out of unconscious functions (as an

"inner view," or mirroring, of the action of the phronema); and at any

time an unconscious process in the cortex may come within the sphere

of consciousness by having the attention directed to it. On the other

hand, conscious actions, which need a good deal of attention when they

are first learned (such as playing the piano), may become unconscious

through frequent repetition and practice. The fact that chemical energy

is converted in the phronetal cells during any of these actions is

proved by the fatigue and exhaustion which prolonged mental work causes

in the brain, just as mechanical work does in the muscles. Fresh matter

has to be supplied by the food before the mental work can be continued.

Moreover, it is well known that various drinks have a considerable

influence on consciousness (coffee and tea, beer and wine); and the

temporary extinction of it under chloroform or ether is an analogous

fact. Again, the familiar phenomena of the dream, the deviations from

normal consciousness, hallucinations, delusions, etc., must convince

every impartial thinker that these mental functions are not of a

metaphysical character, but physical processes in the neuroplasm of the

brain, and thoroughly dependent on the law of substance.

In complete contrast to this natural monistic conception of the

human mind, which is, in my opinion, definitely established by

nineteenth-century science, we have the older dualistic estimate of

it which is still widely accepted both by unlearned and learned,

especially metaphysicians and theologians. I have already dealt in

the _Riddle_ (chapter xi.) with the grounds for this belief in an

immaterial soul, and expressed my conviction that "the belief in the

immortality of the human soul is in flagrant contradiction to the

soundest empirical principles of modern science." I must refer the

reader to what I said there about thanatism and athanatism, only

reminding him once more of the immense influence of the Kantist

philosophy in maintaining this belief in the spirituality of the

soul. Kant derived from the introspective study of his own gifted

mind an extremely high estimate of human reason, and he fallaciously

transferred this estimate to the human mind generally. He did not

perceive that it is either wholly wanting in the savage, or does not

rise much above the stage which has been reached by the intelligence of

the dog, horse, elephant, and other advanced animals.

Modern anthropogeny has raised the theory of evolution to the rank of

an historical fact. All the various organs of our body resemble those

of our nearest relatives, the anthropoid apes, in their structure and

composition. They only differ from them in details of form and size,

which are determined by inherited variations of growth. But the

functions as well as the organs have been inherited by man from his

primate ancestors. This applies to the mind also, which is merely the

collective function of the phronema, the central organ of thought.

An impartial comparison of mental life in the anthropoid ape and

the savage shows that the differences between the two are not more

considerable than the differences in the structure of their brains.

Hence, if one accepts the dualistic theory of the soul formulated by

Plato and Kant and accepted by so many modern psychologists, it is

necessary to attribute an immortal soul to the anthropoid apes and the

higher mammals (especially to domestic dogs) just as well as to savage

or civilized man (_cf._ chapter xi. of the _Riddle_).

The thorough and careful study of the mental life of the savage,

supported by the results of anthropogeny and ethnography, has in the

course of the last forty years decided the issue of this struggle

between the conflicting theories of the origin of civilization. The

older theory of degeneration, based on religious beliefs, and so

preferred by theologians and theosophists, declared that man--the

"image of God"--was created originally with perfect bodily and mental

powers, and only fell away from his high estate after the original

sin. On this view the present savages are degenerate descendants of

the first godlike men. (In tropical lands the anthropoid apes are in

similar fashion regarded by the natives as degenerate branches of

their own stem!) Although this Biblical degeneration theory is still

taught in most of our schools, and even supported by a few mystic

philosophers, it had lost all scientific countenance before the end

of the nineteenth century. It is now replaced by the modern theory

of evolution, which was represented by Lamarck, Goethe, and Herder

a century ago, and raised to a predominant position in ethnography

by Darwin and Lubbock. It has taught us that human civilization is

the outcome of a long and gradual process of evolution, covering

thousands of years. The civilized races of our time have arisen from

less civilized races, and these in turn from lower, until we reach the

savage races which show no trace of civilization.

Ethnologists distinguish as a separate class the races which are found

midway between the civilized peoples and the savages. We shall deal

with their classification and characteristics later on (chapter xvii.).

These races show some advance on the artistic instinct which we find in

a slight degree even among the savages at times; moreover, their animal

curiosity develops into human curiosity, and raises the question of the

causes of phenomena, the germ of all science.

Civilized races, which occupy the next stage to these, are raised above

them by the formation of larger states and a greater division of labor.

The specialization of the various groups of workers and the greater

ease of maintenance permit a further development of art and science. To

these groups belong, of living races, the majority of the Mongolians,

and the greater part of the inhabitants of Europe and Asia in ancient

and mediæval times. The great ancient civilizations of China, Southern

India, Asia Minor, Egypt, and afterwards of Greece and Italy, show not

only a great development of art and science, but also a concern for

legislation, religious worship, education of the young, and the spread

of knowledge by written books.

Civilization in the narrower sense, characterized by a high development

of art and science and the manifold application of them to practical

life in legislation, education, etc., was greatly advanced even in

antiquity among several nations--in Asia by the Chinese, Southern

Indians, Babylonians, and Egyptians; in Europe by the Greeks and Romans

of the classic age. However, their results were at first restricted

to narrow fields, and were mostly lost during the Middle Ages. Modern

civilization rose to importance about the end of the fifteenth century,

when the invention of printing had made possible the spread of

knowledge far and wide, the discovery of America and circumnavigation

of the globe had widened the horizon, and the Copernican system had

demolished the error of geocentricism. Then began the many-sided

growth of civilization which has reached so marvellous a height in the

nineteenth century through the extraordinary development of science.

Then at last free reason could triumph over the prevailing mediæval

superstition.

XV

THE ORIGIN OF LIFE

The miracle of the origin of life--Creation of species: Moses and

Agassiz--Creation of the first cells: Wigand and Reinke--Agnostic

position: resignation--Eternity hypothesis (dualistic, Helmholtz;

monistic, Preyer)--Archigony hypothesis (autogony hypothesis,

Haeckel, Nägeli; cyanic hypothesis, Pflüger, Verworn)--Spontaneous

generation--Saprobiosis or necrobiosis--Experiments in spontaneous

generation--Pasteur--Stages of archigony--Observation of

archigony--Synthesis of plasma--Value of the unsuccessful experiments

to produce plasm artificially--The logic of modern experimental

biology.

The question of the origin of life is one of the most important and

interesting, but one of the most difficult and complicated, problems

with which the mind of man has been occupied for thousands of years.

There are few other questions (such as the freedom of the will or

personal immortality) on which such different and contradictory views

have been expressed, and few that remain so far from being closed

at the present day. There are, moreover, few problems on which the

opinions of even distinguished thinkers diverge so much, and have

degenerated so much into fantastic hypotheses. This is partly due to

the extreme difficulty of giving a strictly scientific solution of

the problem and partly to the confusion of ideas which is so great in

this controversy, the lack of clear rational insight, and the powerful

authority of the prevailing religious faith and other venerable dogmas.

The easiest and quickest thing to do is to cut the Gordian knot of

the question with the sword of faith, or answer it with a belief in

a supernatural creation. The first article of the creed was given

to us in childhood as the foundation of all cosmic philosophy. It

is based on the Mosaic account of creation in the first chapter of

Genesis. As I have fully examined its scientific value in the second

chapter of my _History of Creation_, I may refer the reader thereto.

It is unquestionable that this myth still has a very great practical

influence; the great majority of the clergy cling to it because it is

found in the infallible "word of God." Most governments, which hold

blind faith to be an important element of education, include it in the

code for the elementary school. On the other hand, it is difficult

to find a man of science who will uphold it to-day. The gifted Louis

Agassiz made one of the most remarkable attempts to do this in

his _Essay on Classification_ (1858), a book that appeared almost

contemporaneously with Darwin's epoch-making _Origin of Species_, and

dealt with the general problems of biology from the directly opposite,

the mystic, point of view. According to Agassiz, each species of animal

or plant is an "incarnate thought of the Creator."

Differing from this Biblical fancy of the supernatural creation of

each species, two botanists, Wigand of Marburg and Reinke of Kiel,

have lately restricted the action of the celestial architect very

considerably; they have ascribed to him only the creation of the

primitive cells, which he is supposed to have endowed with the power

to develop into the higher organisms. Wigand assumed for the origin

of each species a special primitive cell and a long phylogenetic

development of this; Reinke prefers a stem, composed of a number of

species. These modern creative theories have no more scientific value

than that of Agassiz; they are equally based on pure superstition

(_cf._ chapters i.-iii.).

A different attitude from this irrational positive superstition is

the sceptical view of those scientists who regard the question of the

origin of life as insoluble or transcendental. Darwin and Virchow are

representatives of this agnostic position; they held that we know

nothing, and can know nothing, about the origin of the first organisms.

Darwin, for instance, explains in his chief work that he "has nothing

to do with the origin of the fundamental spiritual forces, or with

that of life itself." This is a complete abandonment of the task of

solving a scientific problem which must present as definite a subject

of inquiry to modern research as any other evolutionary problem. The

origin of life on our planet represents a fixed point in its history.

However, there is nothing to be said if a scientist chooses to make no

inquiry into it. A number of distinguished modern scientists maintain

this agnostic attitude; they are more or less convinced that the origin

of life is a natural process, but believe we have not as yet the means

to explain it.

Different, again, is a third attitude which regards the problem of

the origin of life as extremely difficult, yet capable of solution.

This is the position of Dubois-Reymond, for instance, who counts the

origin of life as the third great cosmic problem. Most of the modern

scientists who have worked on the problem are of this opinion, although

their views as to the way of solving it differ very much. We are

confronted, in the first place, with two essentially different views

which we may call the eternity-hypothesis and the theory of archigony

(or spontaneous generation). According to the first view, organic life

is eternal; according to the second, it began at a definite point of

time. The eternity-hypothesis has assumed two very different forms, one

of which has a dualistic and the other a monistic base. Helmholtz is a

representative of the former theory, and Preyer of the latter.

Hermann Eberhard Richter put forward, in 1865, the hypothesis that

infinite space is full throughout of the germs of living things,

just as it is of inorganic bodies; both of them are in a condition

of eternal development. When the ubiquitous germs reach a mature and

habitable cosmic body, which possesses heat and moisture in the proper

degrees for their development, they break into life, and may lead to

the formation of a whole world of living things. Richter conceives

these ubiquitous germs as living cells, and formulates the principle:

_Omne vivum ab æternitate e cellula_ (Every living thing is eternal and

from a cell). In much the same way the botanist Anton Kerner postulates

the eternity of organic life and its complete independence of the

inorganic world. But the difficulties encountered by this hypothesis,

in the indefinite form that Kerner gives it, are so great and so

obvious that his theory has won no recognition.

However, the "cosmozoic hypothesis" attained a great popularity when it

was afterwards taken up by two of the most distinguished physicists,

Hermann Helmholtz and Sir W. Thomson (Lord Kelvin). Helmholtz

formulated the alternative thus (in 1884): "Organic life either came

into existence at a certain period, or it is eternal." He declared for

the latter view, on the ground that we have not succeeded in producing

living organisms by artificial means. He supposes that the meteors

that roam about the universe might contain the germs of organisms,

and, under favorable conditions, these might reach the earth or other

planets and develop thereon. This cosmozoic hypothesis of Helmholtz

is untenable, because the physical features of space (the extreme

temperatures, the absolute dryness, the absence of atmosphere, etc.)

exclude the lasting existence of plasm on meteorites in the form of

organic germs with a capacity to live. The hypothesis is, moreover,

logically useless, since it does not solve, but postpones, the

question of the origin of organic life. If it is consistently worked

out, it leads to pure cosmological dualism.

Another and very different theory of the eternity of life has been

elaborated by Theodor Fechner (1873) and Wilhelm Preyer (1880). Both

these scientists extend the idea of life to the whole cosmos, and

reject the distinction that is usually drawn between the organic and

the inorganic. Fechner goes so far as to ascribe consciousness to the

whole universe and every single body in it, and regards individual

organisms merely as parts of one vast universal organism. His system

is, therefore, panpsychistic, and, at the same time, pantheistic, as he

somewhat mystically connects the idea of a conscious God with that of

a living universe. Preyer generally agrees with him in extending the

idea of life to the whole universe, and conceiving it as an organism.

He applies his theory in the symbolic sense which I alluded to on page

38, and described as impracticable. The fiery mass of the forming

earth is the gigantic organism, and Preyer gives the name of "life" to

its rotatory movement (or gravitational energy). As it cooled down,

the heavier metals (the dead inorganic masses) separated from it;

from the rest of it were formed first simple and afterwards complex

carbon-combinations, and finally albumin and plasm. This extension

of the word "organism" has very properly met with little approval in

biology. It only increases the confusion, and the difficulty of marking

off biological from abiological science, which is both practically

necessary and theoretically justified.

If, then, in our opinion, the eternity-hypotheses are of no more

value than the creation-hypotheses, we have left, for the purpose of

answering the great question of the origin of life, only the third

group of scientific theories which I have combined under the general

head or archigony. They start from the following points: 1. Organic

life is everywhere bound up with the plasm (or protoplasm), a chemical

substance of a viscous character, having albuminous matter and water as

its chief constituents. 2. The characteristic movements of this living

substance, to which we give the name of organic life, are physical and

chemical processes, that can only take place within certain limits of

temperature (between the freezing-point and boiling-point of water).

3. Beyond these limits organic life may in certain circumstances be

maintained for a time in a latent condition (apparent death, potential

life); but this latent condition is restricted to a certain (and

generally short) period. 4. As the earth, like all the other planets,

was for a long time in a state of incandescence, at a temperature

of several thousand degrees, living organisms (viscous albuminoids)

cannot possibly have existed on it, and so cannot be eternal. 5.

Fluid water, the first condition for the appearance of organic life,

cannot have formed on it until the crust at the surface had fallen

below boiling-point. 6. The chemical processes which first set in

at this stage of development must have been catalyses, which led to

the formation of albuminous combinations, and eventually of plasm.

7. The earliest organisms to be thus formed can only have been

plasmodomous monera, structureless organisms without organs; the

first forms in which the living matter individualized were probably

homogeneous globules of plasm, like certain of the actual chromacea

(_chroococcus_). 8. The first cells were developed secondarily from

these primitive monera, by separation of the central caryoplasm

(nucleus) and peripheral cytoplasm (cell-body).

The monistic hypothesis of abiogenesis, or autogony (=

self-development) in the strictly scientific sense of the word, was

first formulated by me in 1866 in the second book of the _General

Morphology_. The solid foundation for it was found in the monera I had

described, the very simple organisms without organs that had up to that

time been overlooked or thrust aside. It is of radical importance, in

giving a naturalistic solution of the problem of the origin of life, to

start from these structureless granules of living matter, and not--as

still generally happens--from the cell; these nucleated elementary

organisms could not be the earliest archigonous living things, but

must have been evolved secondarily from the unnucleated monera. Hence,

I made a very thorough study of these rudimentary organisms in my

_Monograph on the Monera_ (1870), and endeavored to formulate it more

clearly later on (in the first volume of the _Systematic Phylogeny_).

In regard to the chemical question of the first formation of plasm

and its inorganic preparation, Edward Pflüger conducted some valuable

investigations, and recognized that the radical of cyanogen was the

chief element of the living plasm. I may therefore distinguish two

different stages of the theory--my own older autogony-hypothesis and

the later cyanogen-hypothesis.

The theory of abiogenesis, or archigony, which I advanced in 1866, and

have developed in later writings, appeals directly to the biochemical

facts that modern vegetal physiology has firmly established. The

chief of these facts is that even the living green plant-cell has the

synthetic faculty of plasmodomism or carbon-assimilation; that is to

say, it is able to build up, by a chemical synthesis and reduction,

from simple inorganic compounds (water, carbonic acid, nitric acid,

and ammonia), the complex albuminous compounds which we call plasm

or protoplasm, and which we regard as the active living substance

and the true material basis of all vital function (_cf._ chapter

vi.). All botanists are now agreed that this most important process

of vegetal life, the fundamental process of all organic life and all

organization, is a purely chemical (or, in the wider sense, physical)

process, and that there is no question of a specific vital force or a

mystic constructor (like the famous "mechanical engineer of life"),

or any other transcendental agency, in connection with it. The tiny

chemical laboratory in which this remarkable organoplastic process

takes place under the influence of sunlight is, in the simplest

plants, the chromacea, either the whole homogeneous globule of plasm

(_chroococcus_) or its bluish-green surface-layer, which is active

as a chromatic principle (chromatophore). But in most plants these

reduction-laboratories are the chromatella or chromatophora, which

have been differentiated from the rest of the plasm of the cell, and

are colorless globular leucoplasts within its dark interior, or green

chromoplasts (or granules of chlorophyll) at its illumined surface.

My theory of archigony only assumes that this chemical process of

plasmodomism which we find repeated every second in every plant-cell

exposed to the sunlight, and which has become an "inherited habit" of

the green plant-cell, developed of itself at the beginning of organic

life; in other words, it is a catalytic process (or one analogous to

catalysis), the physical and chemical conditions of which were present

in the condition of organic nature at that time.

My hypothesis was very strongly confirmed twenty years ago by the

adhesion of the able botanist, Carl Nägeli. In his instructive work,

_A Mechanical-physiological Theory of Evolution_ (1884), he supported

all the principal ideas as to the natural origin of life which I

had advanced in 1866. He formulates the chief part of them in this

admirable principle:

The origin of the organic from the inorganic is, in the first place,

not a question of experience and experiment, but a fact deduced from

the law of the constancy of matter and force. If all things in the

material world are causally related, if all phenomena proceed on

natural principles, organisms, which are formed of and decay into

the same matter, must have been derived originally from inorganic

compounds.

This excellent and clear declaration of a distinguished scientist and

profound thinker might be taken to heart by the "exact" scientists who

are always attacking the monistic theory of archigony as an unproved

hypothesis, or regard the whole problem as insoluble. Nägeli has,

moreover, proceeded to make a thorough study of the molecular processes

involved, and embodied the results in his idioplasm theory. He

believes that at the beginning of organization the definite autonomous

arrangement of the smallest homogeneous parts of the plasm was a

matter of the greatest importance. In his opinion these "micella" are

crystalline groups of molecules, arranged multifariously in strings and

parallel rows.

A similar and more elaborate attempt to give a physical explanation

of the processes of archigony and trace them to mechanical molecular

structures was made by Ludwig Zehnder in 1899 in his work on _The

Origin of Life_. He believes that the smallest and lowest life-unities

(the micellar strings of Nägeli and the biophora of Weismann,

corresponding to my plastidules) have a tubular shape, and so he calls

them "fistella." He supposes that these invisible molecular structures

are regularly arranged in millions in the plasma of the cell, and

differentiated in such a way that some will effect endosmosis, others

contraction, others the conduction of stimuli, and so on. As in

the similar work of Nägeli and others, the value of this molecular

hypothesis is that it stimulates us to attempt to conceive the mode of

the arrangement and movement of the molecules of plasm in the process

of archigony on physical principles.

A more interesting and notable attempt to penetrate into the mysterious

obscurity of the chemical processes in archigony was made in 1875

by the distinguished physiologist, Edward Pflüger, in his essay on

_Physiological Combustion in the Living Organism_. He starts from

the fact that the plasm (or protoplasm) is the material basis of all

vital phenomena, and that this living matter owes its properties to

the chemical properties of the albumin (whether we regard this as a

chemical unity, protein or protalbumin, or as a mixture of different

compounds). However, Pflüger sharply distinguishes between the living

albumin of the plasm out of which all organisms are built, and the dead

albumin, such as we find it, for instance, in the glairy albumin of the

hen's egg. Only the living albumin (plasm) decomposes of itself in a

slight degree, and to a greater extent under the influence of external

excitation; the dead albumin will remain intact for a long time under

favorable conditions. The cause of the extraordinary instability of the

living albumin is its intramolecular oxygen--that is to say, the oxygen

that is taken into the interior of the plasma-molecules in breathing,

and effects there a disassociation, surrounding the atoms and breaking

up the new-formed groups.

The real cause of this rapid decomposability of the plasm, and of the

accompanying formation of carbonic acid, is found in the cyanogen,

a remarkable body composed of an atom of carbon and an atom of

nitrogen, which, in conjunction with potassium, forms the well-known

and very virulent poison, cyanide of potassium. The non-nitrogenous

decomposition-products of the dead and the living albumin agree in the

main, but their nitrogenous products are totally different. Uric acid,

creotin, guanine, and the other decomposition products of plasm contain

the cyanogen-radical, and the most important of all, urea, can be

artificially produced from cyanic compounds, as Wöhler showed in 1828.

From this we may infer that the living albumin always contains the

cyanogen-radical, and that dead nutritive albumin does not. The belief

that it is cyanogen which gives its characteristic vital properties

to the plasm is supported by a number of analogies that we find to

exist between cyanide compounds, especially cyanic acid (C N O H.) and

the living albumin. Both bodies are fluid and transparent at a low

temperature, while they set at a higher; both of them break up in the

presence of water into carbonic acid and ammonia; both produce urea by

disassociation (by the intramolecular surrounding of the atoms, not by

direct oxydation). "The similarity of the two substances is so great,"

says Pflüger, "that I might describe cyanic acid as a semi-living

molecule." Both substances grow in the same way by concatenation of the

atoms, homogeneous groups of atoms joining together chainwise in large

masses.

There is an especial interest in connection with the theory of

archigony and its physical basis in the chemical fact that cyanogen and

its compounds--cyanide of potassium, cyanic acid, cyanide of hydrogen,

etc.--are only formed at incandescent heat; that is to say, when the

requisite inorganic nitrogenous compounds are put with glowing coals,

or the mixture is heated to incandescence. Other essential constituents

of albumin, such as carburetted hydrogen or alcohol-radical, can be

formed synthetically in heat. "Thus," says Pflüger, "nothing is clearer

than the possibility of the formation of cyanic compounds when the

earth was entirely or partially in a state of incandescence or great

heat. We see how extraordinarily all the facts of chemistry point to

fire as the force that has produced the constituents of albumin by

synthesis. Hence life was born from fire, and the chief conditions of

its appearance are associated with a time when the earth was a glowing

ball of fire. When we remember the incalculably long period in which

the surface of the earth was slowly cooling, we see that cyanogen, and

the compounds that contained cyanogen, and carburetted hydrogen, had

plenty of time and opportunity to follow out to any extent their great

tendency to the transposition and formation of polymeria (chains of

atoms), and, with the co-operation of oxygen and afterwards of water

and salts, to evolve into the self-decomposable albumin which is living

matter." In regard to the latter feature, it is well to emphasize the

fact that, as will be understood, there must have been a long series

of chemical intermediary stages between the incandescent formation of

cyanogen and the appearance of the aqueous living plasm.

Pflüger's cyanogen theory does not conflict with my monera theory, but

rather supplements it, by its careful and thoroughly scientific study

of a much earlier stage of primitive biogenesis--in a sense, the first

period of preparation for the formation of albumin. This must be well

borne in mind in view of the attacks which have lately been made on

it by Neumeister and other vitalists; it is supposed to be untenable,

because "there is an impassable gulf between cyanic compounds and

proteids." This criticism is answered by the living albumin itself,

which always contains in its nitrogenous decomposition products the

radical of cyanide or other substances (urea) that can be artificially

produced from cyanic compounds. Another objection is that "the cyanic

compounds which were formed in the heat must have very quickly perished

on the subsequent appearance of water." The objection has no weight,

since we can form no definite idea as to the special conditions of

chemical activity in those times. We can only say that the conditions

during this long period (embracing millions of years) were totally

different from those of chemical action at the surface of the earth

to-day. The real ground of the opposition of Neumeister and other

vitalists is their dualistic conception of nature, which will maintain

at all costs the deep gulf between the organic and inorganic worlds.

Max Verworn, in his _General Physiology_, has fully described and

criticised the various theories of the appearance of life on the earth.

He rightly attributes a great value to Pflüger's cyanogen theory,

because "it makes a strictly scientific study of the problem in close

relation to the facts of physiological chemistry, and goes thoroughly

into detail." He agrees with Pflüger when he expresses himself as

follows: "I would say, therefore, that the first albumin to be formed

was in point of fact living matter, endued with the property in all its

radicals of attracting especially homogeneous parts with great force

and preference, in order to build them chemically into the molecule,

and so grow indefinitely. On this view the living albumin need not

have a constant molecular weight, because it is a huge molecule in an

unceasing process of formation and decomposition, probably acting on

the ordinary chemical molecules as a sun does on a small meteor." This

theory, which I believe to be correct, is also maintained by many other

modern scientists who have made a particular study of the difficult

question of the nature and origin of the albuminoids.

Now that we have described the various modern theories of archigony

that are worth considering, and recognized with Nägeli that the

original development of the organic from the inorganic is a fact, we

may glance at the older theories which, under the name of "spontaneous

generation," afforded matter for a good deal of controversy. It is true

that they are now almost entirely abandoned, but the experiments in

connection with them excited a good deal of interest and led to many

misunderstandings.

The older hypotheses of "spontaneous generation" do not bear on our

problem of archigony (or the first development of living matter from

lifeless inorganic carbon compounds) but relate to the formation of

lower organisms out of the putrid and decomposing organic elements of

higher organisms. In order to distinguish these hypotheses from the

totally different theory of archigony, it is better to give them the

name of saprobiosis (an earlier name was necrobiosis), which means

the birth of living from dead (_nekron_) or putrid (_sapron_) organic

matter. Saprobiosis is preferable, because necrobiosis is better used

in a different sense, for the dead organic parts which gradually bring

about the death of the living body (see p. 106). It was believed in

ancient times that lower organisms could arise from the dead remains of

higher organisms, such as fleas from manure, lice from morbid pustules

in the skin, moths from old furs, and mussels from slime in the water.

As these stories were supported by the authority of Aristotle, and

on that account believed by St. Augustine and other fathers, and

reconciled with the faith, they were held until the beginning of the

eighteenth century. Even in the year 1713 the botanist Heucherus stated

that the green duck-weed (_lemna_) is only condensed grease from the

surface of foul standing water, and that water-cress was formed from it

in fresh running water.

The first scientific refutation of these old stories was made by the

Italian physician, Francisco Redi, in 1674, on the basis of very

careful experiment: he was persecuted for "unbelief" on that account.

He showed that all these animals arose from eggs that had been

deposited by female animals in dung, skin, fur, slime, etc. But at that

time the proof could not be extended to the tape-worms, maw-worms,

and other intestinal animals (_entozoa_), which live inside other

animals (in the bowels, blood, brain, or liver). It was still believed

that these arise from diseased parts of the host-animals in which

they live, until about the middle of the nineteenth century. It was

not until 1840-1860 that it was shown by the experiments of Siebold,

Leuckart, Van Beneden, Virchow, and other famous biologists, that all

these intestinal animals have come from without into the animals they

live in, and propagate there by eggs. Of late years the proof has been

applied all round.

On the other hand, the hypothesis of saprobiosis retained its position

until quite recently for one section of the smallest and lowest

organisms, the microscopic forms of life, invisible to the naked eye,

which were formerly called infusoria, and which we now call by the

wider name of protists or unicellulars. When Leeuwenhoek discovered the

infusoria in 1675 with the newly invented microscope, and showed that

they arise in great quantities in infusions of hay, moss, flesh, and

other putrid organic substances, it was generally believed that they

were spontaneously generated there. The Abbé Spallanzani showed in 1687

that no infusoria appear in these infusions if they are well boiled and

the vessel is carefully closed; the boiling kills the germs in them,

and the exclusion of air prevents the entrance of fresh germs. In spite

of this, many microscopists still believed that certain infusoria,

particularly the very small and simple bacteria, could be born directly

from putrid or diseased tissues of organisms, or from decomposing

organic fluids; the opinion was maintained by Pouchet at Paris in 1858,

and afterwards by Charlton Bastian. The controversy about the subject

moved the Paris Academy in 1858 to offer a prize for "careful research

that would throw new light on the question of spontaneous generation."

It fell to the famous Louis Pasteur, who proved, by a series of

ingenious experiments, that there are everywhere in the atmosphere

numbers of germs of microbes or microscopic organisms floating among

the dust particles, and that these grow and reproduce when they reach

water. Not only infusoria, but also small highly organized plants and

animals--such as lichens, mosses, rotifers, and tardigrades--can live

for months in a desiccated condition, be carried in all directions

by the wind, and reawaken into life when they reach water. On the

other hand, Pasteur showed convincingly that organisms never appear

in infusions of organic substances when they are sufficiently boiled

and the atmosphere that reaches them has been chemically purified. He

summed up the results of his rigorous experiments, which were confirmed

by Robert Koch and other bacteriologists, and gave rise to the modern

precautions as to disinfection, in the maxim: "Spontaneous or equivocal

generation is a myth."

The famous experiments of Pasteur and his successors had destroyed the

myth of saprobiosis, but not the theory of archigony. These entirely

different hypotheses are still very frequently confused, because the

old title of "spontaneous generation" is used for both. We still read

sometimes that the "unscientific" belief in abiogenesis has been

definitely refuted by these experiments, and that the question of

the origin of life has thus become an insoluble enigma. There is an

astonishing superficiality and lack of discernment in such remarks;

they would hardly be possible in any other branch of science. But in

biology--many of its distinguished representatives continue to say--we

have only to observe and correctly describe facts; the formation

of clear ideas and the indulgence in reflection on the facts are

unnecessary and dangerous, and, therefore, to be avoided! It is due

to this pitiable condition of biological methods of research that

our hypothesis of archigony is still attacked, or else ignored. Why?

Because the false hypothesis of saprobiosis, which has absolutely

nothing in common with it but the name "spontaneous generation," has

been refuted by the experiments of Pasteur and his colleagues![9]

These experiments prove nothing whatever beyond the fact that new

organisms are not formed in certain infusions of organic matter--under

definite, artificial conditions. They do not even touch the important

and pressing question, which alone interests us: "How did the earliest

organic inhabitants of our earth, the primitive organisms, arise from

inorganic compounds?"

The great popularity of the famous experiments of Pasteur on

spontaneous generation, and the unfortunate confusion of ideas which

was caused by the false interpretation of his results, make it

necessary for me to say a word on the general value of scientific

experiments in many questions. Since Bacon introduced experiment into

science three hundred years ago, and gave it a logical basis, both

our speculative knowledge of nature and the practical application

of our knowledge made remarkable progress. New methods of research

made it possible for modern workers to penetrate far more deeply into

the nature of phenomena than the older thinkers had done, who had no

knowledge of experiment. Especially in the nineteenth century the

development of the experimental method, or the putting of a question to

nature, led to enormous advances in the various sciences.

In the subject we are considering the question to be put to nature

is: "Under what conditions and in what manner is living matter (or

plasm) formed from lifeless inorganic compounds?" We may confidently

assume that in the period when archigony took place--the time when

organic life first appeared on the cooled surface of the earth, at

the beginning of the Laurentian Age--the conditions of existence were

totally different from what they are now; but we are very far from

having a clear idea of what they were, or from being able to reproduce

them artificially. We are just as far from having a thorough chemical

acquaintance with the albuminous compounds to which plasm belongs.

We can only assume that the plasma-molecule is extremely large, and

made up of more than a thousand atoms, and that the arrangement and

connection of the atoms in the molecule are very complicated and

unstable. But of the real features of this intricate structure we

have as yet no conception. As long as we are ignorant of this complex

molecular structure of albumin, it is useless to attempt to produce

it artificially. Yet in this position of the matter we would seek

to produce that great wonder of life, the plasm, artificially, and

when the experiment miscarries (as we should expect) we cry out:

"Spontaneous generation is impossible."

When we carefully consider the intelligent experiments that have been

made in regard to archigony in the light of these facts, it is clear

that their negative result does not in the slightest degree affect our

question. The much-admired experiments of Pasteur and his colleagues

prove merely that in certain artificial conditions infusoria are not

formed in decomposing organic compounds (or the dead tissues of highly

organized histona); they cannot possibly prove that saprobioses of this

kind do not take place under other conditions. They tell us nothing

whatever about the possibility or reality of archigony; in the form

in which I put the scientific hypothesis in 1866 it is completely

untouched by all these experiments. It remains intact as the first

attempt to give a provisional reply--if only in the form of a temporary

hypothesis--on the basis of modern science to one of the chief

questions of natural philosophy.

In my _General Morphology_ (1866), and afterwards in my _Biological

Studies on the Monera and other Protists_, and the first volume of

my _Systematic Phylogeny_ (1894), I attempted to sketch in detail

the stages of the process to which I give the name of archigony. I

distinguished two principal stages--_autogony_ (the formation of the

first living matter from inorganic nitrogenous carbon-compounds) and

_plasmogony_ (the formation of the first individualized plasm; the

earliest organic individuals in the form of monera). In more recent

efforts I have made use of the important results reached by Nägeli

(1884) in his investigations of the same subject. In regard to some

important points relating to the chemico-physical part of the question,

Nägeli has, in his _Mechanico-physiological Theory of Evolution_

(chapter ii.), gone more into the details of the process of archigony.

To the earliest living things, which were formed by "unicellular

organization" of the plasm out of simple inorganic compounds, he

gives the name of _probia_ or _probionta_, and thinks that these had

an even simpler structure than my monera. This view seems to rest on

a misunderstanding. Nägeli does not strictly follow my definition,

"organisms without organs" (that is to say, structureless living

particles of plasm without morphological differentiation), but he has

in mind the individual rhizopod-like organisms which I had at first

described as monera--_protamœba_, _protogenes_, _protomyxa_, etc. In

my present view the chromacea, or plasmodomous phytomonera, are much

more important than these plasmophagous zoomonera. It is curious that

Nägeli does not make thorough use of their primitive organization for

the establishment of his theory, although he has had the great merit of

describing these most primitive of all living organisms as unicellular

algæ (1842). As a matter of fact, the simplest chromacea (chroococcus

and related forms) approach so closely to his hypothetical probia

or probionta that the only things we can regard as the rudiments of

organization in the chroococcacea are the secretion of a protective

membrane about the homogeneous plasma-globule and the separation of

the blueish-green cortical zone from the colorless central granule.

The more important of the further conclusions of Nägeli are those

which relate to the mode of the primitive abiogenesis and the frequent

repetition of this physical process.

Recently Max Kassowitz, in the second volume of his _General Biology_

(1899), has gone fully into the various stages of the process of

archigony, as a sequel to his metabolic theory of the building up and

decay of plasm, from the point of view of physiological chemistry. He

says very truly that the development of living from lifeless matter

must not be conceived as a sudden leap; the very complicated chemical

unities which now form the basis of life have been slowly and gradually

evolved during an incalculably long period by the way of substitution

for simpler compounds. We may join these views--which generally accord

with my earlier deductions--with Pflüger's cyanogen theory, and so draw

up the following theses:

1. A preliminary stage to archigony is the formation of certain

nitrogenous carbon-compounds which may be classed in the cyanic

group (cyanic acid, etc.). 2. When the crust of the earth stiffened,

water was formed in the fluid condition; under its influence, and in

consequence of the great changes in the carbonic-acid laden atmosphere,

a series of complicated nitrogenous carbon-compounds were formed from

these simple cyanic compounds, and these first produced albumin (or

protein). 3. The molecules of albumin arranged themselves in a certain

way, according to their unstable chemical attractions, in larger groups

of molecules (pleona or micella). 4. The albumin-micella combined to

form larger aggregations, and produced homogeneous plasma-granules

(plassonella). 5. As they grew the plassonella divided, and

formed larger plasma-granules of a homogeneous character: monera

(= probionta). 6. In consequence of surface-strain or of chemical

differentiation, there took place a separation of the firmer cortical

layer (membrane) from the softer marrow layer (central granule), as in

many of the chromacea. 7. Afterwards the simplest (nucleated) cells

were formed from these unnucleated cytodes, the hereditary mass of the

plasm gathering within the monera and condensing into a firm nucleus.

It is an interesting, but at present unanswered, question whether the

process of archigony only occurred once in the course of time or was

frequently repeated. Reasons can be given for both views. Pflüger

says: "In the plant the living albumin only continues to do what it

has done ever since its origin--constantly to regenerate itself or to

grow; hence I believe that all the albumin in the world comes from that

source. On that account I doubt if spontaneous generation takes place

in our time. Moreover, comparative biology directly shows that all life

has come from one single root." However, this view does not exclude the

possibility of the chemical process of spontaneous plasmodomism having

been frequently repeated--under like conditions--in the same form in

primordial times.

On the other side, Nägeli especially has pointed out that there is

no reason to prevent us from thinking that archigony was repeated

several times, even down to our own day. Whenever the physical

conditions for the chemical process of plasmodomism were given, it

might be repeated anywhere at any time. As to locality, the sea-shore

probably affords the most favorable conditions; as, for instance, on

the surface of fine moist sand the molecular forces of matter in all

its conditions--gaseous, fluid, viscous, and solid--find the best

conditions for acting on each other. It is a fact that to-day all the

various evolutionary forms of living matter--from the simplest moneron

(chroococcus) to the plain nucleated cell, from this to the highly

organized cell of the radiolaria and infusoria, from the simple ovum to

the most elaborate tissue-structure in the higher plants and animals,

from the amphioxus to man--come in an order of succession. There are

only two ways of explaining this fact: either the simplest living

organisms, the chromacea and bacteria, the palmella and amœbæ, have

remained unchanged or made very little advance in organization since

the beginning of life--more than a hundred million years; or else

the phylogenetic process of their transformation has been frequently

repeated in the course of this period, and is being repeated to-day.

Even if the latter were the case, we should hardly be in a position to

learn it by direct observation.

Assuming that the simplest organisms are still formed by abiogenesis,

the direct observation of the process would probably be impossible,

or at least extremely difficult, for the following reasons: 1. The

earliest and simplest organisms are most probably globular particles

of plasm, without any visible structure, like the simplest living

chromacea (_chroococcus_). 2. These plasmodomous monera cannot be

distinguished from the chromoplasts (chlorophyll-granules), which live

inside plant-cells, and may continue after the death of the cells

to multiply independently by cleavage. 3. We must admit with Nägeli

that the original size of these probionta (in spite of the relatively

colossal size of their molecules) is very small--much too small to

come within the range of the best microscope. 4. In the same way the

primitive metabolism and the slow, simple growth of these monera would

not come within direct observation. 5. As a matter of fact, we do often

find in stagnant water, and in the sea, tiny granules which consist, or

seem to consist, of plasm. We usually regard them as detached portions

of dead animals or plants; little isolated chlorophyll-granules that

may be found everywhere are looked upon as rejected products of vegetal

cells. But who could refute the assumption that they are really

plassonella or young monera, which grow slowly and unite with similar

particles to form larger plasmic bodies?

It is often objected to our naturalistic and monistic conception of

archigony that we have not yet succeeded in forming albuminous bodies,

and especially plasm, in our chemical laboratories by artificial

synthesis; from this the perverse dualistic conclusion is drawn that

it is only supernatural vital forces that can do this. It is forgotten

that we do not yet know the complicated structure of albuminous

bodies, and that we do not yet know what really happens inside the

green chlorophyll-granules which in every plant-cell convert the

radiant energy of sunlight into the virtual energy of the new-formed

plasm. How can we be expected to reproduce synthetically, with the

imperfect and crude methods of present chemistry, an elaborate chemical

process the nature of which is not analytically known to us? However,

the worthlessness of this sceptical objection is obvious: we can

never claim that a natural process is supernatural because we cannot

artificially reproduce it.

XVI

THE EVOLUTION OF LIFE

Inorganic and organic evolution--Biogenesis and

cosmogenesis--Mechanical evolution--Mechanics of phylogenesis--Theory

of selection--Theory of idioplasm--Phyletic vital force--Theory of

germ-plasm--Progressive heredity--Comparative morphology--Germ-plasm

and hereditary matter--Theory of mutation--Zoological and botanical

transformism--Neo-Lamarckism and Neo-Darwinism--Mechanics of

ontogenesis--Biogenetic law--Tectogenetic ontogeny--Experimental

evolution--Monism and biogeny.

I fully explained in my _General Morphology_ (1866) the profound

importance of the science of evolution in relation to our monistic

philosophy. A popular synopsis of this is given in my _History of

Creation_, and is briefly repeated in the thirteenth chapter of the

_Riddle_. I must refer the reader to these works, especially the

latter, and confine myself here to a consideration of some of the

principal general questions of evolution in the light of modern

science. The first thing to do is to compare the conflicting views on

the nature and significance of biogenesis which still face each other

at the beginning of the twentieth century.

The essential unity of inorganic and organic nature, which I endeavored

to establish in the second book of the _General Morphology_, and the

significance of which I explained in the fourteenth chapter of the

_Riddle_, is found through the whole course of its development, in

the causes of phenomena and their laws. Hence, in dealing with the

evolution of organisms, we reject vitalism and dualism, and maintain

our conviction that it can always be traced to physical forces (and

especially chemical energy). As we regard plasm as the basis of it

(chapter vi.), we may say that organic evolution depends on the

mechanics and chemistry of the plasm. We postulate no supernatural

vital force for the explanation of physiological functions, and we are

just as far from admitting it as regulator or agency of the biogenetic

process.

If we understand by biogeny the sum total of the organic evolutionary

processes on our planet, by geogeny the processes at work in the

formation of the earth itself, and by cosmogony those that produced the

whole world, biogeny is clearly only a small part of geogeny, and this

in turn only a small section of the vast science of cosmogony. This

important relation is evident enough, yet often overlooked; it holds

both of time and space. Even if we suppose that the biogenetic process

occupied more than a hundred million years, this period is probably

much shorter than that which our planet has needed for its development

as a cosmic body--from the first detachment of the nebular ring from

the shrinking body of the sun to its condensation into a rotating

sphere of gas, and from this to the formation of the incandescent

globe, the stiffening of the crust at its surface, and finally the

downpour of fluid water. It was not until this last stage that carbon

could begin its organogenetic activity and proceed to the formation of

plasm. But even this long geogenetic process is, as regards space and

time, only a very small part of the illimitable history of the world.

If we further assume that organic life develops on other cosmic bodies

(_Riddle_, chapter xx.) in the same way as on our earth under like

conditions, the whole sum of all these biogenetic processes is only a

small part of the all-embracing cosmogenetic process. The vitalistic

belief that its mechanical course was interrupted from time to time

by the supernatural creation of organisms is opposed to pure reason,

the unity of nature, and the law of substance. We must, therefore, hold

fast above all to the conviction that all biogenetic processes are

just as reducible to the mechanics of substance as all other natural

phenomena.

The mechanical and natural character of the development of inorganic

nature, the earth and the whole material world, was established

mathematically at the end of the eighteenth century by the great

atheist Laplace in his _Mécanique Céleste_ (1799). The similar

cosmogony which Kant had expounded in 1755 in his _General Natural

History and Theory of the Heavens_ only obtained recognition at a

later date (_Riddle_, chapter xiii.). But the possibility of giving

a mechanical explanation of organic nature was not seen until Darwin

provided a solid foundation for the theory of descent by his theory of

selection in 1859. I made the first comprehensive attempt to do this in

1866 in my _General Morphology_, the aim of which is expressed in the

title: "General outlines of the science of organic forms, mechanically

grounded on Darwin's improvement of the theory of descent." Especially

in the second volume of the work, the "General Evolution of Organisms,"

I endeavored to show that both sections of the science, ontogeny (or

embryology) and phylogeny, can be reduced to physiological activities

of the plasm, and so explained mechanically, in the wider meaning of

the word.

When I stated the nature and the aim of phylogeny in 1866, most

biologists regarded my attempt as unjustifiable, as they did Darwinism

itself, of which it was a natural consequence. Even the famous Émil

Dubois-Reymond, to whom as a physiologist it should have been welcome,

described it as "a poor romance"; he compared my first attempts

to construct the genealogical tree of the organic classes, on the

evidence of paleontology, comparative anatomy, and ontogeny, to the

hypothetical labors of philologists to draw up the genealogical tree

of the legendary Homeric heroes. As a matter of fact, I had myself

described my imperfect effort as merely a provisional sketch, as a

temporary hypothesis that would open the way for later and better

research. A single glance at the immense literature of phylogeny

to-day shows how much has been done since in this province, and how

far we have advanced in the establishment of the features of evolution

by means of the united labors of numbers of able paleontologists,

anatomists, and embryologists. Ten years ago I attempted, in the three

volumes of my _Systematic Phylogeny_, to give a comprehensive statement

of the results attained. My chief aim was, on the one hand, to

construct a natural system of organisms on the basis of their ancestral

history, and on the other hand to prove the mechanical character of

the phylogenetic process. All the activities of organisms which are at

work in the transformation of species and the production of new ones

in the struggle for existence may be reduced to their physiological

functions--to growth, nutrition, adaptation, and heredity; and these

again to the mechanics and chemistry of the plasm. The struggle for

life is itself a mechanical process, in which natural selection uses

the disproportion between the excess of germs and the restricted

means of existence, in conjunction with the variability of species,

in order to produce new purposive structures mechanically and without

any preconceived design. This teleological mechanicism has no need of

a mysterious design or finality; it takes its place in the general

order of mechanical causality which controls all the processes in the

universe. Natural finality is only a special instance of mechanical

causality. The one is subordinate to the other, not opposed to it, as

Kant would have it.

The effort that the great Lamarck made in 1809, in his _Philosophie

Zoologique_, to establish transformism deserves high appreciation from

monists, because it was the first attempt to give a natural explanation

of the origin of the countless species of organic forms which inhabit

our planet. Up to that time it had been the fashion to attribute their

origin to a miraculous intervention of the Creator. This metaphysical

creationism had now to face physical evolutionism. Lamarck explained

the gradual formation of organic species by the interaction of

two physiological functions--adaptation and heredity. Adaptation

consists in the improvement of organs by use, and degeneration by

disuse; heredity acts by transmitting the features thus acquired to

posterity. New species arise by physiological transformation from

older species. The fact that this great thought was overlooked for

half a century does not detract from its profound significance. But it

only obtained general recognition when Darwin had supplemented it and

filled up its causal gaps by the theory of selection in 1859. Apart

from this specifically Darwinian feature (whether it be true or not),

the fundamental idea of transformism is now generally received; it

is admitted to-day even by metaphysicians who maintained a spirited

opposition to it thirty years ago. The fact of the progressive

modification of species is only intelligible on Lamarck's theory

that the actual species are the transformed descendants of older

species. In spite of all the learning and zeal with which the theory

has been attacked, it has proved irrefutable; nor can any one suggest

a better theory to replace it. This may be said particularly of its

chief consequence--the descent of man from a series of other mammals

(proximately from the apes).

The high value of Darwin's theory of selection for the monistic biology

is now acknowledged by all competent and impartial authorities

on the science. In the course of the forty-four years since it

found its way into every branch of biology, it has been employed

in more than a hundred large works and several thousand essays in

explaining biological phenomena. This alone is enough to show its

profound importance. Hence it is mere ignorance of the subject and

its literature to say, as has been done several times of late, that

Darwinism is in decay, or even "dead and buried." However, absurd

writings of this kind (such as Dennert's _At the Death-bed of

Darwinism_) have a certain practical influence, because they fall

in with the prevailing superstition in theology and metaphysics.

Unfortunately, they also seem to obtain notice from the circumstance

that a few botanists persistently attack the Darwinian theory. One of

the most conspicuous of these is Hans Driesch, who affirms that all

Darwinists (and therefore the great majority of modern biologists) have

softening of the brain, and that Darwinism is (like Hegel's philosophy)

the delusion of a generation. The arrogance of this conceited writer is

about equal to the obscurity of his biological opinions, the confusion

of which is covered by a series of most extravagant metaphysical

speculations. All these attacks have lately been met very ably by

Plate in his work, _On the Significance of the Darwinian Principle

of Selection and the Problem of the Foundation of Species_ (second

edition, 1903). The most thorough of recent defences of Darwinism

is that made by August Weismann in his _Lectures on the Theory of

Descent_ (1902) and other works. But the distinguished zoologist

goes too far when he seeks to prove the omnipotence of selection and

wishes to ground it on an untenable molecular hypothesis--the theory

of germ-plasm, which we will consider presently. Apart from these or

other exaggerations, we may say with Weismann that Lamarck's theory of

descent received a sound causal basis by Darwin's theory of selection.

Its real foundations are these three phenomena: heredity, adaptation,

and the struggle for existence. All three are, as I have often said,

of a purely mechanical and not a teleological nature. Heredity is

closely bound up with the physiological function of reproduction, and

adaptation with nutrition; the struggle for life follows logically and

mathematically from the disproportion between the number of potential

individuals (germs) and of actual individuals that grow to maturity and

propagate the species.

When I had, in my _General Morphology_, endeavored to gain acceptance

for Darwin's theory of selection, and had presented evolution as a

comprehensive theory from the point of view of the monistic philosophy,

a number of works, sometimes of value, appeared, which made special

studies of the various parts of the immense province. Eighteen years

afterwards a greater work was published, which started from the same

monistic principles, but reached the same conclusion by a different

way. In 1884 Carl Nägeli, one of our ablest and most philosophic

botanists, issued his _Mechanical-physiological Theory of Evolution_.

This interesting book consists of various parts. It is especially

notable that evolution is presented in it as the one possible

and natural theory of the origin of species; even morphology and

classification are treated explicitly as "phylogenetic sciences." The

chapter on archigony--a dark and dangerous problem that is generally

avoided by scientists!--is one of the best that has been written on the

subject. On the other hand, Nägeli rejects Darwin's theory of selection

altogether, and would explain the origin of species by an inner

"definitely directed variation," independently of the conditions of

existence in the outer world. As Weismann has properly observed, this

internal principle of evolution, which dispenses with adaptation in

the true sense of the word, is at the bottom merely a "phyletic vital

force." It is not made more acceptable by Nägeli when he builds up a

subtle metaphysical system on it and postulates a special "principle

of isagitation." But the idioplasm theory he connects with it is of

some value, since it goes more fully into the differentiation of the

cell-plasm into two physiologically different parts--the idioplasm of

the hereditary matter and the trophoplasm as nutritive matter of the

cell.

The vitalist and teleological idea of an internal principle of

evolution, that determines the origin of animal and plant species

independently of the environment and its conditions, is not only

found in the "mechanical-physiological" theory of Nägeli, but also in

several other attempts to explain the agencies of the transformation of

species. All these efforts are welcomed by the academic philosophers

with their Kantist dualism (mechanicism on the right, teleology on

the left), and who are particularly anxious to save the supernatural

element, Reinke's "cosmic intelligence," or the wisdom of the Creator,

or the divine creative thought. All these dualistic and teleological

efforts have the same fault: they overlook, or fail to appreciate

properly, the immense influence of the environment on the shaping

and modification of organisms. When, moreover, they deny progressive

heredity and its connection with functional adaptation, they lose the

chief factor in transformation. This applies also to the theory of

germ-plasm.

The desire to penetrate deeper into the mysterious processes that

take place in the plasm in the physiological activities of heredity

and adaptation has led to the formulation of a number of molecular

theories. The chief of these are the pangenesis theory of Darwin

(1878), my own perigenesis theory (1876), the idioplasm theory of

Nägeli (1884), the germ-plasm theory of Weismann (1885), the mutation

theory of De Bries, etc. As I have already dealt with these in the

sixth chapter (as well as in the ninth chapter of the _History of

Creation_), I may refer the reader thereto. None of these or similar

attempts has completely solved the very difficult problems in question,

and none of them has been generally received. There is, however, one

of them that we must consider more closely, because it is not only

regarded by many biologists as the greatest advance of the theory of

selection since Darwin, but it also touches the roots of several of

the chief problems of biogeny. I mean the much-discussed germ-plasm

theory of August Weismann (of Freiburg), one of our most distinguished

zoologists. He has not only promoted the theory of descent by his

many writings during the last thirty years, but has also put in its

proper light the great importance and entire accuracy of the theory of

selection. But, in his efforts to provide a molecular-physiological

basis for it, he has proceeded by way of metaphysical speculation to

frame a quite untenable theory of the plasm. While fully recognizing

the ability and consistency and the able treatment which Weismann

has shown, I am compelled once more to dissent from him. His ideas

have recently been completely refuted by Max Kassowitz (1902) in his

_General Biology_, and Ludwig Plate in the work I mentioned on the

Darwinian principle of selection. We need not go into the details of

the complicated hypothesis as to the molecular structure of the plasm

which Weismann has framed in support of his theory of heredity--his

theory of biophora, determinants, ideas, etc.--because they have no

theoretical basis and are of no practical use. But we must pass some

criticism on one of their chief consequences. In the interest of his

complicated hypotheses, Weismann denies one of Lamarck's most important

principles of transmutation--namely, the inheritance of acquired

characters.

When I made the first attempt in 1866 to formulate the phenomena of

heredity and adaptation in definite laws and arrange these in series,

I drew a distinction between conservative and progressive heredity

(chapter ix., _History of Creation_). Conservative heredity, or the

inheritance of inherited characters, transmits to posterity the

morphological and physiological features which each individual has

received from his parents. Progressive heredity, or the inheritance of

acquired characters, transmits to offspring a part of those features

which were acquired by the parents in the course of their individual

lives. The chief of these are the characters that are caused by the

activity of the organs themselves. Increase in the use of the organs

causes a greater access of nourishment and promotes their growth;

decrease in the exercise of organs has the contrary effect. We have

examples at hand in the modification of the muscles or the eyes, the

action of the hand or throat in painting or singing, and so on. In

these and all the arts the rule is: Practice makes perfect. But this

applies almost universally to the physiological activity of the plasm,

even its highest and most astounding function--thought; the memory and

reasoning capacity of the phronema are improved by constant exercise of

the cells which compose this organ, just as we find in the case of the

hands and the senses.

Lamarck recognized the great morphological significance of this

physiological use of the organs, and did not doubt that the

modification caused was transmitted to offspring to a certain extent.

When I dealt with this correlation of direct adaptation and progressive

heredity in 1866, I laid special stress on the "law of cumulative

adaptation" (_General Morphology_, ii., p. 208). "All organisms undergo

important and permanent (chemical, morphological, and physiological)

changes when acted on by a change in its life-conditions, slight in

itself, but continuing for a long time or being frequently repeated."

At the same time I pointed out that in this case two groups of

phenomena are closely connected which are often separated--namely,

cumulative heredity: firstly _external_, by the action of the external

conditions (food, climate, environment, etc.), and secondly _internal_,

by the reaction of the organism, the influence of internal conditions

(habit, use and disuse of organs, etc.). The action of outer influences

(light, heat, electricity, pressure, etc.) not only causes a reaction

of the organism affected (energy of movement, sensation, chemosis,

etc.), but it has an especial effect as a trophic stimulus on its

nutrition and growth. The latter element has been particularly studied

by Wilhelm Roux; his functional adaptation (1881) coincides with my

cumulative adaptation, the close relation of which to correlative

adaptation I had pointed out in 1866. Plate has recently given this

"definitely directed variation" the name of ectogenetic orthogenesis,

or, briefly, ectogenesis.

The controversy about progressive heredity still continues here and

there. Weismann completely denies it, because he cannot bring it into

harmony with his germ-plasm theory, and because he thinks there are

no experimental proofs in support of it. A number of able biologists

agree with him, led away by his brilliant argumentation. However,

many of them foolishly lay great stress on experiments in heredity

which prove nothing; for instance, the fact that the offspring of a

mammal that has had its tail cut off do not inherit the feature. A

number of recent observations seem to prove that in a few cases even

defects of this sort (when they have caused profound and lasting

disease of the part affected) may be transmitted to offspring.

However, as far as the formation of new species is concerned, the

fact is of no consequence; in this it is a question of cumulative or

functional adaptation. Experimental proofs of this are difficult to

find, if one wants a strict demonstration of the type of physical

experiments; the biological conditions are generally too complicated

and offer too many weak points to rigorous criticism. The beautiful

experiments of Standfuss and C. Fisher (Zurich) have shown that changes

in the environment (such as temperature or food) can cause striking

modifications that are transmitted to offspring. In any case, there are

plenty of luminous proofs of progressive heredity in the vast arsenal

of morphology, comparative anatomy, and ontogeny.

Comparative anatomy affords a number of most valuable arguments for

other phylogenetic questions as well as progressive heredity; and the

same may be said of comparative anatomy and comparative ontogeny. I

have collected and illustrated a good many of these proofs in the new

edition of my _Anthropogeny_. However, in order to understand and

appreciate them aright, the reader must have some acquaintance with

the methods of critical comparison. This means not only an extensive

knowledge of anatomy, ontogeny, and classification, but also practice

in morphological thinking and reasoning. Many of our modern biologists

lack these qualifications, especially those "exact" observers who

erroneously imagine they can understand vast groups of phenomena by

accurate description of detailed microscopic structures, etc. Many

distinguished cytologists, histologists, and embryologists have

completely lost the larger view of their work by absorption in these

details. They even reject some of the fundamental ideas of comparative

anatomy, such as the distinction between homology and analogy;

Wilhelm His, for instance, declared that these "academic ideas" are

"unreliable tools." On the other hand, physiological experiments ought

to contribute to the solution of morphological problems, and of these

they can say nothing. To show the incalculable value of comparative

anatomy for phylogeny, I need only point to one of its most successful

departments, the skeleton of the vertebrates, the comparison of the

various forms of the skull, the vertebral column, the limbs, etc. It

is not in vain that for more than a hundred years gifted scientists,

from Goethe and Cuvier to Huxley and Gegenbaur, have devoted years

of laborious research to the methodical comparison of these similar

yet dissimilar forms. They have been rewarded by the discovery of the

common laws of structure, which can only be explained in the sense of

modern evolution by descent from common ancestors.

We have a striking example of this in the limbs of mammals, which, with

the same internal skeletal structure, show a very great variety in

outer form--the slender bones of the running carnivora and ungulates,

the oar-bones of the whale and seal, the shovel-bones of the mole and

hypudæus, the wings of the bat, the climbing bones of the ape, and the

differentiated limbs of the human body. All these different skeletal

forms have descended from the same common stem-form of the oldest

Triassic mammals; their various forms and structures are adapted in

scores of ways to different functions; but they rise _through_ these

functions, and all these functional adaptations can only be understood

by progressive heredity. The theory of germ-plasm gives no causal

explanation whatever of them.

The majority of recent biologists are of opinion that of the two chief

constituents of the nucleated cell the cytoplasm of the cell-body

discharges the function of nutrition and adaptation, while the

caryoplasm of the nucleus accomplishes reproduction and heredity.

I first advanced this view in the ninth chapter of the _General

Morphology_ (in 1866); and it was afterwards solidly and empirically

established by the excellent investigations of Eduard Strasburger, the

brothers Oscar and Richard Hertwig, and others. The elaborate finer

structures which these observers discovered in cell-division led to

the theory that the colorable part of the nucleus, chromatin, is the

real hereditary matter, or the material substratum of the energy of

heredity. Weismann added the theory that this germ-plasm lives quite

separately from the other substances in the cell, and that the latter

(the soma-plasm) cannot transmit to the germ-plasm the characters it

has acquired by adaptation. It is on the strength of this theory that

he opposes progressive heredity. The representatives of the latter

(including myself) do not accept this absolute separation of germ-plasm

from body-plasm; we believe that even in the process of cell-division

in the unicellular organism there is partial blending of the two kinds

of plasm (caryolysis), and that in the multicellular organism of the

histona also the harmonious connection of all the cells by their

plasma-fibres makes it possible enough for all the cells in the body to

act on the germ-plasm of the germ-cells. Max Kassowitz has shown how we

can explain this influence by the molecular structure of the plasm.

At the beginning of the twentieth century a new biological theory

aroused a good deal of interest, and was welcomed by some as an

experimental refutation of Darwin's theory of selection and by others

as a valuable supplement to it. The distinguished botanist Hugo de

Bries (of Amsterdam) gave an interesting lecture at the scientific

congress at Hamburg in 1901 on "The Mutations and Mutation-periods

in the Origin of Species." Supported by many years of experiments in

selection and some ingenious speculations, he thinks he has discovered

a new method of the transformation of species, an abrupt modification

of the specific form at a bound, and so discredited Darwin's theory of

their gradual change through long periods of time. In a large work on

_Experiments and Observations on the Origin of Species in the Plant

Kingdom_ (1903), De Bries has endeavored to demonstrate the truth of

his theory of mutation. The warm approval which it won from a number

of eminent botanists, and especially vegetal physiologists, was not

shared by zoologists. Of these Weismann, in his _Lectures on the

Theory of Descent_ (1902, ii. p. 358), and Plate in his _Problems of

Species-formation_ (1903, p. 174), have dealt fully with the theory

of mutation, and, while appreciating the interesting observations

and experiments of De Bries, have rejected the theory he has built

on them. As I share their opinion, I may refer the reader who is

interested in these difficult problems to their works, and will

restrict myself here to the following observations. The chief weakness

of the theory of mutation of De Bries is on its logical side, in

his dogmatic distinction between species and variety, mutation and

variation. When he holds the constancy of species as a fundamental

"fact of observation," we can only say that this (relative) permanence

of species is very different in the different classes. In many

classes (for instance, insects, birds, many orchids and graminea) we

may examine thousands of specimens of a species without finding any

individual differences; in other classes (such as sponges, corals, in

the genera _rubus_ and _hieracium_) the variability is so great that

classifiers hesitate to draw up fixed species. The marked difference

between various forms of variability which De Bries alleges cannot

be carried through; the fluctuating variations (which he takes to be

unimportant) cannot be sharply distinguished from the abrupt mutations

(from which new species are supposed to result at a bound). De Bries's

mutations (which I distinguished in the _General Morphology_ as

"monstrous changes" from other kinds of variation) must not be confused

with the paleontological mutations of Waagen (1869) and Scott (1894)

which have the same name. The sudden and striking changes of habit

which De Bries observed only in one single species of _œnothera_

very rarely occur, and cannot be regarded as common beginnings of

the formation of new species. It is a curious freak of chance that

this species bears the name _œnothera Lamarckiana_; the views of

the great Lamarck on the powerful influence of functional adaptation

have not been refuted by De Bries. It must be carefully noted, in

fact, that De Bries is firmly convinced of the truth of Lamarck's

theory of descent, like all competent modern biologists. This must be

well understood, because recent metaphysicians see in the supposed

refutation of Darwinism the death of the whole theory of transformism

and evolution. When they appeal in this sense to its most virulent

opponents, Dennert, Driesch, and Fleischmann, we may remind them that

the curious sermons of these minor sophists are no longer noticed by

any competent and informed scientist.

Not only in the brilliant speculations of De Bries and Nägeli, but

also in many other botanical works that have lately attempted to

advance the theory of descent, we find a striking difference from

the prevailing views of zoologists in the treatment of a number of

general biological problems. This difference is, of course, not

due to a disproportion of ability in the two great and neighboring

camps of biology, but to the differences in the phenomena that we

observe in plant life on the one hand and animal life on the other.

It must be noted particularly that the organism of the higher animals

(including our own) is much more elaborately differentiated in its

various organs and much more exposed to our direct experience than

that of the higher plants. The chief properties and activities of our

muscles, skeleton, nerves, and sense-organs, are understood at once

in comparative anatomy and physiology. The study of the corresponding

phenomena in the bodies of the higher plants is much more difficult.

The features of the innumerable elementary organs in the cell-monarchy

of the animal body are much more intricate, yet at the same time much

more intelligible, than those of the cell-republic of the higher

plant-body. Thus the phylogeny of the plants encounters much greater

difficulties than that of the animals; the embryology of the former

says much less in detail than that of the latter. We can understand,

therefore, why the biogenetic law is not so generally recognized by

botanists as by zoologists. Paleontology, which provides such valuable

fossil material for many groups of the animal kingdom that we can

more or less correctly draw up their ancestral tree on the strength

of this, gives us very little for most groups of the plant kingdom.

On the other hand, the large and sharply demarcated plant-cell, with

its various organella, is much more valuable in connection with many

problems than the tiny animal-cell. For many physiological purposes,

in fact, the higher plant body is more accessible to exact physical

and chemical research than the higher animal body. The antithesis is

less in the kingdom of the protists, as the difference between animal

and vegetal life is mostly confined to difference of metabolism, and

finally disappears altogether in the province of the unicellular forms

of life. Hence, for a clear and impartial treatment of the great

problems of biology, and especially of phylogeny, it is imperative to

have a knowledge of both zoological and botanical investigation. The

two great founders of the theory of descent--Lamarck and Darwin--were

able to penetrate so deeply into the mysteries of organic life and its

development because they had extensive attainments both in botany and

zoology.

Of the various tendencies that have recently made their appearance

among zoologists and botanists in the discussion of the theory

of descent, we frequently find Neo-Lamarckism and Neo-Darwinism

distinguished as opposing schools. This opposition has no meaning

unless we understand by it the alternatives of transformism--with or

without the theory of selection. The one principle that distinguishes

Darwinism proper from the older Lamarckism is the struggle for

existence and the theory of selection based on it. It is quite wrong

to make the test an acceptance or rejection of progressive heredity.

Darwin was just as firmly convinced as Lamarck or myself of the great

importance of the inheritance of acquired characters, and particularly

of the inheritance of functional adaptations; he merely ascribed to it

a more restricted sphere of influence than Lamarck. Weismann, however,

denies progressive heredity altogether, and wants to trace everything

to "the omnipotence of natural selection." If this view of Weismann

and the theory of germ-plasm he has based on it are correct, he alone

has the honor of founding a totally new (and in his opinion very

fruitful) form of transformism. But it is quite wrong to describe this

Weismannism as Neo-Darwinism, as frequently happens in England. It is

just as wrong to call Nägeli, De Bries, and other modern biologists who

reject selection Neo-Lamarckists.

If the theory of descent is right, as all competent biologists now

admit, it puts on morphology the task of assigning approximately the

origin of each living form. It must endeavor to explain the actual

organization of each by its past, and to recognize the causes of its

modification in the series of its ancestors. I made the first attempt

to achieve this difficult task in founding stem-history or phylogeny

as an independent historical science in my "General Evolution" (in

the second volume of the _General Morphology_). With it I associated

as a second and equally sound part ontogeny; I understood by this the

whole science of the development of the individual, both embryology and

metamorphology. Ontogeny enjoys the privileges (especially in the way

of certainty) of a purely descriptive science, when it confines itself

to the faithful description of the directly observed facts, either the

embryonic processes in the womb or the later metamorphic processes.

The task of phylogeny is much more difficult, as it has to decipher

long-past processes by means of imperfect evidence, and has to use its

documents with the utmost prudence.

The three most valuable sources of evidence in phylogeny are

paleontology, comparative anatomy, and ontogeny. Paleontology seems

to be the most reliable source, as it gives us tangible facts in

the fossils which bear witness to the succession of species in the

long history of organic life. Unfortunately, our knowledge of the

fossils is very scanty and often very imperfect. Hence the numerous

gaps in its positive evidence have to be filled up by the results of

two other sciences, comparative anatomy and ontogeny. I have dealt

fully with this in my _Anthropogeny_. As I have also spoken of the

general features of these phyletic evidences in the sixteenth chapter

of the _History of Creation_, I need do no more here than repeat

that it is necessary to make equal and discriminating use of all

three classes of documents if we are to attain the aim of phylogeny

correctly. Unfortunately, this necessitates a thorough knowledge of

all three sciences, and this is very rare. Most embryologists neglect

paleontology, most paleontologists embryology, while comparative

anatomy, the most difficult part of morphology, involving most

extensive knowledge and sound judgment, is neglected by both. Besides

these three sources of phylogeny there is valuable proof afforded

by every branch of biology, especially by chorology, œcology,

physiology, and biochemistry.

Although there has been very extensive phylogenetic research during the

last thirty years, and it has yielded a number of interesting results,

many scientists still seem to look on them with a certain distrust;

some contest their scientific value altogether, and say that they are

nothing but airy and untenable speculations. This is especially the

case with many physiologists who look upon experiment as the only

exact method of investigation, and many embryologists who think their

sole task is description. In view of these sceptical strictures, we

may recall the history and the nature of geology. No one now questions

the great importance and the various uses of this science, although

in it there is no possibility of directly observing the historical

processes as a rule. No scientist now doubts that the three vast

successive formations of the Mesozoic Period--the Triassic, Jurassic,

and Cretaceous--have been formed from sea-deposits (lime, sandstone,

and clay), though no one was a witness to the actual formation; no one

doubts to-day that the fossil skeletons of fishes and reptiles which

we find in these groups are not mysterious freaks of nature, but the

remains of extinct fishes and reptiles that lived on the earth during

those millions of years long ago. And when comparative anatomy shows us

the genealogical connection of these related forms, and phylogeny (with

the aid of ontogeny) constructs their ancestral trees, their historical

hypotheses are just as sound and reliable as those of geology; the

only difference is that the latter are much simpler, and thus easier

to construct. Phylogeny and geology are, in the nature of the case,

_historical sciences_.

Hypotheses are necessary in phylogeny and geology, where the empirical

evidence is incomplete, as in every other historical science. It is no

detraction from the value of these to urge that they are sometimes weak

and have to be replaced by better and stronger ones. A weak hypothesis

is always better than none. We must, therefore, protest against the

foolish dread of hypotheses which is urged against our phylogenetic

methods by the representatives of the exact and descriptive sciences.

This shrinking from hypotheses often hides a defective knowledge of

other sciences, an incapacity for synthetic thought, and a feeble sense

of causality. The delusions into which it leads many scientists may be

seen from the fact that chemistry, for instance, is reckoned an "exact"

science; yet no chemist has ever seen the atoms and molecules of

compounds with which he is occupied daily, or the complicated relations

on the assumption of which the whole of modern structural chemistry

is based. All these hypotheses rest on inferences, not on direct

observation.

I have, from the first, insisted on the close causal connection between

ontogeny and phylogeny, ever since I distinguished these two parts of

biogeny in the fifth book of the _General Morphology_. I also laid

stress on the mechanical character of these sciences, and endeavored

to give a physiological explanation of their morphological phenomena.

Until then embryology had been regarded as a purely descriptive

science. Carl Ernst Baer, who had provided a solid foundation for it

in his classic _Animal Embryology_ (1828), was convinced that all the

phenomena of individual development might be reduced to the laws of

growth; but he was quite unconscious of the real direction of this

growth, its "purposiveness," the real causes of construction. The

distinguished Würtzburg anatomist, Albert Kölliker, whose _Manual of

Human Embryology_ (1859) gave the first comprehensive treatment of the

science from the cellular point of view, adhered, even in the fourth

edition (1884), to the opinion that "the laws of the development of

the organism are still completely unknown." In opposition to this

generally received opinion, I endeavored, in 1866, to prove that Darwin

had, by his improvement of the theory of descent, not only solved

the phylogenetic problem of the origin of species, but, at the same

time, given us the key to open the closed doors of embryology, and to

learn the causes of the ontogenetic processes as well. I formulated

this view in the twentieth chapter of the _General Morphology_, in

forty-four theses, of which I will quote only the following three: 1.

The development of organisms is a physiological process, depending on

mechanical causes, or physico-chemical movements. 40. Ontogenesis, or

the development of the organic individual, is directly determined by

phylogenesis, or the evolution of the organic stem (_phylon_) to which

it belongs. 41. Ontogenesis is a brief and rapid recapitulation of

phylogenesis, determined by the physiological functions of heredity and

adaptation. The pith of my biogenetic principle is expressed in these

and the remaining theses on the causal nexus of biontic and phyletic

development. At the same time I make it quite clear that I reduce the

physical process of ontogenesis, and also phylogenesis, to a pure

mechanics of the plasm (in the sense of the critical philosophy).

The comprehensive fundamental law of organic development was briefly

formulated by me in the fifth book of the _General Morphology_ and in

the tenth chapter of the _History of Creation_ (developed more fully

in the fourteenth chapter of the tenth edition, 1902). I afterwards

sought to establish it securely in two different ways. In the first

place, I proved in my _Studies of the Gastræa Theory_ (1872-1877)

that in all the tissue-animals, from the lowest sponges and polyps to

the highest articulata and vertebrates, the multicellular organism

develops from the same primitive embryonic form (the _gastrula_),

and that this is the ontogenetic repetition, in virtue of heredity,

of a corresponding stem-form (the _gastræa_). In the second place, I

made the first attempt in my _Anthropogeny_ (1874) to illustrate this

recapitulation theory from the instance of our own human organism, by

trying to explain the complex process of individual development, for

the whole frame and every single part of it, by causal connection with

the stem-history of our animal ancestors. In the latest edition of this

monistic "ontogeny of man" I gave numbers of illustrations (thirty

plates and five hundred engravings) of these intricate structures,

and endeavored to make the subject still plainer by the addition of

sixty genetic tables. I may refer the reader to this work,[10] and

not dwell any further here on the biogenetic law, especially as one

of my pupils, Heinrich Schmidt (of Jena), has recently described its

biological significance and its earlier history and present position in

a very clear and reliable little work (_Haeckel's Biogenetic Law and

its Critics_). I will only add a word or two on the struggle that has

taken place for thirty years over the complete or partial recognition

of the biogenetic law, its empirical establishment, and its philosophic

application.

In the very name, "fundamental law of biogeny," which I have given to

my recapitulation theory, I claim that it is universal. Every organism,

from the unicellular protists to the cryptogams and cœlenteria, and

from these up to the flowering plants and vertebrates, reproduces in

its individual development, in virtue of certain hereditary processes,

a part of its ancestral history. The very word "recapitulation"

implies a partial and abbreviated repetition of the course of the

original phyletic development, determined by the "laws of heredity

and adaptation." Heredity brings about the reproduction of certain

evolutionary features; adaptation causes a modification of them by

the conditions of the environment--a condensation, disturbance, or

falsification. Hence I insisted from the first that the biogenetic law

consists of two parts, one positive and palingenetic and the other

restrictively negative and cenogenetic. _Palingenesis_ reproduces a

part of the original history of the stem; _cenogenesis_ disturbs or

alters this picture in consequence of subsequent modifications of the

original course of development. This distinction is most important, and

cannot be too often repeated in view of the persistent misunderstanding

of my opponents. It is overlooked by those who (like Plate and

Steinmann) grant it only a partial validity, and by those who reject

it altogether (like Keibel and Hensen). The embryologist Keibel is the

most curious of these, as he has himself afforded a good many proofs

of the biogenetic law in his careful descriptive-embryological works.

But he has so little mastered it that he has never understood the

distinction between palingenesis and cenogenesis.

It is especially unfortunate that one of our most distinguished

embryologists, Oscar Hertwig, of Berlin, who provided a good deal of

evidence in favor of the biogenetic law thirty years ago, has lately

joined the opponents of it. His supposed "correction" or modification

of it is, as Keibel has rightly said, a complete abandonment of it.

Heinrich Schmidt has partly explained the causes of this change

in his work on the biogenetic law. They are not unconnected with

the psychological metamorphosis which Oscar Hertwig has undergone

at Berlin. In the discourse on "The Development of Biology in the

Nineteenth Century," which he delivered at the scientific congress at

Aachen in 1900, he openly accepted the dualist principles of vitalism

(although he says they are "just as unreliable as the chemico-physical

conception of the opposing mechanical school"). The views which he has

lately advanced on the worthlessness of Darwinism and the unreliability

of phylogenetic hypotheses are diametrically opposed to the opinions

he represented at Jena twenty-five years ago, and to those which his

brother, Richard Hertwig, of Munich, has consistently maintained in his

admirable _Manual of Zoology_.

In opposition to the mechanical ontogeny which I formulated in 1866

and embodied in the biogenetic law, a number of other tendencies

in embryology afterwards appeared, and, with the common title of

"mechanical embryology," branched out in every direction. The chief of

these to attract attention thirty years ago were the pseudo-mechanical

theories of Wilhelm His, who has rendered great service to ontogeny

by his accurate descriptions and faithful illustrations of

vertebrate-embryos, but who has no idea of comparative morphology,

and so has framed the most extraordinary theories about the nature

of organic development. In his _Study of the First Sketch of the

Vertebrate-body_ (1868), and many later works, His endeavored to

explain the complicated ontogenetic phenomena on direct and simple

physical lines by reducing them to elasticity, bending, folding of the

embryonic layers, etc., while explicitly rejecting the phylogenetic

method; he says that this is "a mere by-way, and quite unnecessary for

the explanation of the ontogenetic facts (as direct consequences of

physiological principles of development)." As a matter of fact, nature

rather plays the part of an ingenious tailor in His's pseudo-mechanical

and tectogenetic speculations, as I have shown in the third chapter of

the _Anthropogeny_. Hence they have been humorously called the "tailor

theory." However, they misled a few embryologists by opening the way

to a direct and purely mechanical explanation of the complex embryonic

phenomena. Although they were at first much admired, and immediately

afterwards abandoned, they have found a number of supporters lately in

various branches of embryology.

The great success that modern experimental physiology achieved by its

extensive employment of physical and chemical experiments inspired a

hope of attaining similar results in embryology by means of the same

"exact" methods. But the application of them in this science is only

possible to a slight extent on account of the great complexity of the

historical processes and the impossibility of "exactly" determining

historical matters. This is true of both branches of evolution,

individual and phyletic. Experiments on the origin of species have

very little value, as I said before; and this is generally true of

embryological experiments also. However, the latter, especially

careful experiments on the first stages of ontogenesis, have yielded

some interesting results, particularly in regard to the physiology

and pathology of the embryo at the earliest stages of development.

The _Archiv für Entwickelungsmechanik_, which is edited by the chief

representative of this school, Wilhelm Roux, contains, besides these

valuable inquiries, a good number of ontogenetic articles, which partly

rely on and partly ignore the biogenetic law.

Psychology and biogeny have been up to the present regarded as the

most difficult branches of biology for monistic explanation, and the

strongest supports of dualistic vitalism. Both departments become

accessible to monism and a mechanico-causal explanation by means

of the biogenetic law. The close correlation which it establishes

between individual and phyletic development, and which depends on the

interaction of heredity and adaptation, makes it possible to explain

both. In regard to the first, I formulated the following principle

thirty years ago in my first study of the gastræa theory: "Phylogenesis

is the mechanical cause of ontogenesis." This single principle clearly

expresses the essence of our monistic conception of organic development:

In the future every student will have to declare himself for or

against this principle, if in biogeny he is not content with a mere

admiration of the wonderful phenomena, but desires to understand

their significance. The principle also makes clear the wide gulf

that separates the older teleological and dualistic morphology from

the modern mechanical and monistic science. If the physiological

functions of heredity and adaptation are proved to be the sole causes

of organic construction, every kind of teleology, and of dualistic

and metaphysical explanation, is excluded from the province of

biogeny. The irreconcilable opposition between the leading principles

of the two is clear. Either there is or is not a direct and causal

connection between ontogeny and phylogeny. Either ontogenesis is a

brief compendium of phylogenesis or it is not. Either epigenesis and

descent--or pre-formation and creation.

In repeating these principles here, I would lay stress particularly on

the fact that, in my opinion, our "mechanical biogeny" is one of the

strongest supports of the monistic philosophy.

XVII

THE VALUE OF LIFE

Changes of life--Aim of life--Progress of life--Historic

aims--Historic waves--Value of life in classes and races of

men--Psychology of uncivilized races--Savages--Barbarians--Civilized

nations--Educated nations--Three stages of development (lower,

middle, and higher) in each of the four classes--Individual and

social value of civilized life in the five sections of nutrition,

reproduction, movement, sensation, and mental life--Estimate of human

life.

The value of human life is seen by us to-day, now that evolution is

established, in quite a different light from fifty years ago. We are

now accustomed to regard man as a natural being, the most highly

developed natural being that we know. The same "eternal iron laws"

that rule the evolution of the whole cosmos control our own life.

Monism teaches that the universe really deserves its name, and is an

all-embracing unified whole--whether we call it God or Nature. Monistic

anthropology has now established the fact that man is but a tiny part

of this vast whole, a placental mammal, developed from a branch of

the order of primates in the later Tertiary Period. Hence, before we

seek to estimate the value of man's life, we will cast a glance at the

significance of organic life generally.

An impartial survey of the history of organic life on our planet

teaches, first of all, that it is a process of constant change.

Millions of animals and plants die every second, while other millions

replace them; every individual has his definite period of life,

whether it lives only a few hours, like the one-day fly or the

infusorium, or, like the Wellingtonia, the dragon-tree of Orotava, and

many other giant trees, lives for thousands of years. Even the species,

the collection of like individuals, is just as transitory, and so are

the orders and classes that embrace numbers of species of animals and

plants. Most species are confined to a single period of the organic

history of the earth; few species or genera pass unchanged through

several periods, and not a single one has lived in all the periods.

Phylogeny, taking its stand on the facts of paleontology, teaches

unequivocally that every specific living form has only existed a longer

or shorter period in the course of the many (more than a hundred)

million years which make up the history of organic life.

Every living being is an end to itself. On this point all unprejudiced

thinkers are agreed, whether, like the teleologist, they believe in an

entelechy or dominant as regulator of the vital mechanism, or whether

they explain the origin of each special living form mechanically by

selection and epigenesis. The older anthropistic idea, that animals

and plants were created for man's use, and that the relations of

organisms to each other were generally regulated by creative design,

is no longer accepted in scientific circles. But it is just as true of

the species as of the individual that it lives for itself, and looks

above all to self-maintenance. Its existence and "end" are transitory.

The progressive development of classes and stems leads slowly but

surely to the formation of new species. Every special form of life--the

individual as well as the species--is therefore merely a biological

episode, a passing phenomenal form in the constant change of life. Man

is no exception. "Nothing is constant but change," said the old maxim.

The historical succession of species and classes is, both in the

animal and the plant kingdom, accompanied by a slow and steady

progress in organization. This is directly and positively taught by

paleontology; its creation-medals, the fossils, are unequivocal and

irrefutable witnesses to this phylogenetic advance. I have dealt with

the subject in my _History of Creation_, and at the same time shown

that both the progressive improvement and the increasing variety of

the species can be explained mechanically as necessary consequences of

selection. There was no need of a conscious Creator or a transcendental

purposiveness to effect this. Scientific and thorough proof of this

will be found in the three volumes of my _Systematic Phylogeny_ (1894).

I need only refer briefly to the two conspicuous examples we have in

the stem-history of the tissue-plants and that of the vertebrates. Of

the metaphyta the ferns are the chief groups in the Paleozoic, the

gymnosperms in the Mesozoic, and the angiosperms in the Cenozoic age.

Of the vertebrates only fishes are found in the Silurian age, dipneusta

only begin in the Devonian, and the first mammals are in the Triassic.

A number of false teleological conclusions have been drawn from these

facts of progressive modification of forms, as they are given in

paleontology. The latest and most developed form of each stem was

taken to be the preconceived aim of the series, and its imperfect

predecessors were conceived as preparatory stages to the attainment

of this aim. It was like the conduct of many historians, who, when

a particular race or state has reached a high rank in civilization

as a result of its natural endowments and favorable conditions of

development, hail it as a "chosen people," and regard its imperfect

earlier condition as a deliberately conceived preparatory stage.

In point of fact, these evolutionary stages were bound to proceed

according as the internal structure (given by heredity) and the outer

conditions (provoking adaptation) determined. We cannot admit any

conscious direction to a certain end, either in the form of theistic

predestination or pantheistic finality. For this we must substitute a

simple mechanical causality in the sense of psycho-mechanical monism or

hylozoism.

Although the stem-history of plants and animals, like the history of

humanity, shows a progressive advance taken as a whole, we find a

good deal of vacillation in detail. These historical waves are wholly

irregular; in periods of decay the hollows of the waves often persist

for a long time, and are then succeeded by a fresh rise to the crest

of another wave. New and rapidly advancing groups come to take the

place of the old decaying groups, bringing with them a higher stage

of organization. Thus, for instance, the ferns of to-day are only a

feeble survival of the huge and varied pteridophyta that formed the

most conspicuous part of the paleozoic forests in the Devonian and

Carboniferous periods; they were ousted in the Secondary Period by

their gymnosperm descendants (cycadea and conifers), and these, again,

in the Tertiary Period by the angiosperm flowering plants. So among the

terrestrial reptiles the modern tortoises, serpents, crocodiles, and

lizards are only a feeble remnant of the enormous reptile-fauna that

dominated the Secondary Period, the colossal dinosauri, pterosauri,

ichtyosauri, and plesiosauri. They were replaced in the Tertiary

Period by the smaller but more powerful mammals. In the history of

civilization the Middle Ages form a deep valley between the crests of

the waves of classical antiquity and modern culture.

These few examples suffice to show that the various classes and orders

of living things have a very different value when compared with each

other. In regard to their intrinsic aim, self-maintenance, it is true

that all organisms are on a level, but in their relations to other

living things and to nature as a whole they are of very unequal

value. Not only may larger animals and plants retain domination for a

long time in virtue of their special use or superior force and mass,

but small ones may prevail owing to their power of inflicting injury

(bacteria, fungi, parasites, etc.). In the same way the value of the

various races and nations is very unequal in human history. A small

country like Greece has almost dominated the mental life of Europe

for more than two thousand years in virtue of its superior culture.

On the other hand, the various tribes of American Indians have, it is

true, developed a partial civilization in some parts (Peru and Central

America); but, on the whole, they have proved incapable of advancing.

Though the great differences in the mental life and the civilization

of the higher and lower races are generally known, they are, as a

rule, undervalued, and so the value of life at the different levels is

falsely estimated. It is civilization and the fuller development of the

mind that makes civilization possible, that raise man so much above

the other animals, even his nearest animal relatives, the mammals. But

this is, as a rule, peculiar to the higher races, and is found only

in a very imperfect form or not at all among the lower. These lower

races (such as the Veddahs or Australian negroes) are psychologically

nearer to the mammals (apes or dogs) than to civilized Europeans; we

must, therefore, assign a totally different value to their lives. The

views on the subject of European nations which have large colonies in

the tropics, and have been in touch with the natives for centuries,

are very realistic, and quite different from the ideas that prevail in

Germany. Our idealistic notions, strictly regulated by our academic

wisdom and forced by our metaphysicians into the system of their

abstract ideal-man, do not at all tally with the facts. Hence we can

explain many of the errors of the idealistic philosophy and many of

the practical mistakes that have been made in the recently acquired

German colonies; these would have been avoided if we had had a better

knowledge of the low psychic life of the natives (_cf._ the writings of

Gobineau and Lubbock).

The grave errors that have been maintained in psychology for centuries

are mostly due to a neglect of the comparative and genetic methods and

the narrow employment of self-observation, or the introspective method;

they are also partly due to the fact that metaphysicians generally make

their own highly developed mind--a scientifically trained reason--the

starting-point of their inquiry, and regard this as representative of

the human mind in general, and thus build up their ideal scheme. The

gulf between this thoughtful mind of civilized man and the thoughtless

animal soul of the savage is enormous--greater than the gulf that

separates the latter from the soul of the dog. Kant would have avoided

many of the defects of his critical philosophy, and would not have

formulated some of his powerful dogmas (such as the immortality of the

soul, or the categorical imperative) if he had made a thorough and

comparative study of the lower soul of the savage, and phylogenetically

deduced the soul of civilized man therefrom.

The extreme importance of this comparison has only been fully

appreciated of late years (by Lubbock, Romanes, etc.). Fritz Schultze

(of Dresden) made the first valuable attempt in his interesting

_Psychology of the Savage_ (1900) to give us an "evolutionary

psychological description of the savage in respect of intelligence,

æsthetics, ethics, and religion." At the same time, he gives us "a

history of the natural creation of the human imagination, will, and

faith." The first book of this important work deals with thought, the

second with will, and the third with the religious ideas of the savage,

or "the story of the natural evolution of religion" (fetichism,

animism, worship of the heavenly bodies). In an appendix to the second

book the author deals with the difficult problems of evolutionary

ethics, supporting himself by the authority of the great work of

Alexander Sutherland, _The Origin and Growth of the Moral Instinct_

(1898). Sutherland divides humanity, in regard to the various stages of

civilization and mental development (not according to racial affinity),

into four great classes: 1, Savages; 2, barbarians; 3, civilized

races; 4, educated races. As this classification of Sutherland's not

only enables us to take a good survey of the various forms of mental

development, but is also very useful in connection with the question of

the value of life at the different stages, I will briefly reproduce the

chief points of his characterization of the four classes.

I. SAVAGES.--Their food consists of wild natural products (the fruits

and roots of plants, and wild animals of all kinds). Most of them are,

therefore, fishers or hunters. They are ignorant of agriculture and the

breeding of cattle. They live isolated lives in families or scattered

in small groups, and have no fixed home. The lowest and oldest savages

come very close to the anthropoid apes from which they have descended,

in bodily structure and habits. We may distinguish three orders in this

class--the lower, middle, and higher savages.

_A._ Lower savages, approaching nearest to the ape, pygmies of

small stature, four to four and a half feet high (rarely four and

three-quarters); the women sometimes only three to three and a half

feet. They are woolly haired and flat-nosed, of a black or dark brown

color, with pointed belly, thin and short legs. They have no homes, and

live in forests and caverns, and partly on trees; wander about in small

families of ten to forty persons; quite naked, or with just a trace of

some primitive garment. Of the lower races now living we must put in

this class the Veddahs of Ceylon, the Semangs of the Malay Peninsula,

the Negritos of the Philippines, the Andaman Islanders, the Kimos of

Madagascar, the Akkas of Guinea, and the Bushmen of South Africa. Other

scattered remnants of these ancient negroid dwarfs, which approach

closely to the anthropoid apes, still live in various parts of the

primitive forests of the Sunda Islands (Borneo, Sumatra, Celebes).

The value of the life of these lower savages is like that of the

anthropoid apes, or very little higher. All recent travellers who have

carefully observed them in their native lands, and studied their bodily

structure and psychic life, agree in this opinion. Compare the thorough

treatment of the Veddahs of Ceylon in the work of the brothers Sarasin

(of which I have given a summary in my _Travels in Ceylon_). Their only

interests are food and reproduction, in the same simple form in which

we find these among the anthropoid apes (_cf._ chapters xv. and xxiii.

of my _Anthropogeny_). Our own ancestors were probably much the same

ten thousand or more years ago. On the strength of fossil remains of

Pleistocene men Julius Kollmann has shown it to be very probable that

similar dwarf races (with an average height of four and a half feet)

inhabited Europe at that time.

_B._ Middle savages, somewhat larger and less apelike than the

preceding, averaging five to five and a half feet in height. Their

homes are rock caverns and shelters from the wind and rain. Though

they have shirts and other rudiments of clothing, both sexes generally

go naked; they have primitive weapons of wood and stone and rudely

fashioned boats, wander in troops of fifty to two hundred, and have

no social organization; certain races, however, have laws. To this

group belong the Australian negroes and Tasmanians, the Ainos of

Japan, the Hottentots, Fuegians, Macas, and some of the forest races of

Brazil. The value of their life is very little superior to that of the

preceding order.

_C._ Higher savages, mostly of average human height (smaller in colder

regions), having always simple dwellings (generally of skins or the

bark of trees). They have always primitive clothing, and good weapons

of stone, bronze, or copper. They wander in troops of one hundred to

five hundred, led by prominent but not ruling princes, and exhibiting

rudimentary differences of rank. The method of life is determined

by hereditary customs. To this group belong many of the primitive

inhabitants of India (Todas, Nagas, Curumbas, etc.), the Nicobar

Islanders, the Samoyeds, and Kamtschadals; in Africa, the negroes of

Damara; and most of the Indian tribes of North and South America. Their

life is higher than that of the pithecoid lower and middle savages, but

less than that of the barbarians.

II. BARBARIANS OR SEMI-SAVAGES.--The greater part of their food

consists of natural products, which they secure with some foresight;

hence they have developed agriculture and pasture to a greater or less

extent. The division of labor is slight, each family supplying its

own wants. As a rule, a stock of food is provided for the whole year.

As a result of this, art begins to develop. They have generally fixed

dwellings.