Besides tasting, there are two functions conducive to life, which the

tongue performs. It enables us to move about food during mastication, and

it enables us to make many of the articulations constituting speech. But

how does the extreme discriminativeness of the tongue-tip aid these

functions? The food is moved about, not by the tongue-tip, but by the body

of the tongue; and even were the tip largely employed in this process, it

would still have to be shown that its ability to distinguish between points

one-twenty-fourth of an inch apart, is of service to that end, which cannot

be shown. It may, indeed, be said that the tactual perceptiveness of the

tongue-tip serves for detection of foreign bodies in the food, as

plum-stones or as fish-bones. But such extreme perceptiveness is needless

for the purpose. A perceptiveness equal to that of the finger-ends would

suffice. And further, even were such extreme perceptiveness useful, it

could not have caused survival of individuals who possessed it in slightly

higher degrees than others. It needs but to observe a dog crunching small

bones, and swallowing with impunity the sharp-angled pieces, to see that

but a very small amount of mortality would be prevented.

But what about speech? Well, neither here can there be shown any advantage

derived from this extreme perceptiveness. For making the _s_ and _z_, the

tongue has to be partially applied to a portion of the palate next the

teeth. Not only, however, must the contact be incomplete, but its place is

indefinite--may be half an inch further back. To make the _sh_ and _zh_,

the contact has to be made, not with the tip, but with the upper surface of

the tongue; and must be an incomplete contact. Though, for making the

liquids, the tip of the tongue and the sides of the tongue are used, yet

the requisite is not any exact adjustment of the tip, but an imperfect

contact with the palate. For the _th_, the tip is used along with the edges

of the tongue; but no perfect adjustment is required, either to the edges

of the teeth, or to the junction of the teeth with the palate, where the

sound may equally well be made. Though for the _t_ and _d_ complete contact

of the tip and edges of the tongue with the palate is required, yet the

place of contact is not definite, and the tip takes no more important share

in the action than the sides. Any one who observes the movements of his

tongue in speaking, will find that there occur no cases in which the

adjustments must have an exactness corresponding to the extreme power of

discrimination which the tip possesses: for speech, this endowment is

useless. Even were it useful, it could not be shown that it has been

developed by survival of the fittest; for though perfect articulation is an

aid, yet imperfect articulation has rarely such an effect as to impede a

man in the maintenance of his life. If he is a good workman, a German's

interchanges of _b's_ and _p's_ do not disadvantage him. A Frenchman who,

in place of the sound of _th_, always makes the sound of _z_, succeeds as a

teacher of music or dancing, no less than if he achieved the English

pronunciation. Nay, even such an imperfection of speech as that which

arises from cleft palate, does not prevent a man from getting on if he is

capable. True, it may go against him as a candidate for Parliament, or as

an "orator" of the unemployed (mostly not worth employing). But in the

struggle for life he is not hindered by the effect to the extent of being

less able than others to maintain himself and his offspring. Clearly, then,

even if this unparalleled perceptiveness of the tongue-tip is required for

perfect speech, such use is not sufficiently important to have been

developed by natural selection.

How, then, is this remarkable trait of the tongue-tip to be accounted for?

Without difficulty, if there is inheritance of acquired characters. For the

tongue-tip has, above all other parts of the body, unceasing experiences of

small irregularities of surface. It is in contact with the teeth, and

either consciously or unconsciously is continually exploring them. There is

hardly a moment in which impressions of adjacent but different positions

are not being yielded to it by either the surfaces of the teeth or their

edges; and it is continually being moved about from some of them to others.

No advantage is gained. It is simply that the tongue's position renders

perpetual exploration almost inevitable; and by perpetual exploration is

developed this unique power of discrimination. Thus the law holds

throughout, from this highest degree of perceptiveness of the tongue-tip to

its lowest degree on the back of the trunk; and no other explanation of the

facts seems possible.

"Yes, there is another explanation," I hear some one say: "they may be

explained by _panmixia_." Well, in the first place, as the explanation by

_panmixia_ implies that these gradations of perceptiveness have been

arrived at by the dwindling of nervous structures, there lies at the basis

of the explanation an unproved and improbable assumption; and, in the

second place, even were there no such difficulty, it may with certainty be

denied that _panmixia_ can furnish an explanation. Let us look at its

pretensions.

* * * * *

It was not without good reason that Bentham protested against metaphors.

Figures of speech in general, valuable as they are in poetry and rhetoric,

cannot be used without danger in science and philosophy. The title of Mr.

Darwin's great work furnishes us with an instance of the misleading effects

produced by them. It runs:--_The Origin of Species by means of Natural

Selection, or the Preservation of favoured Races in the Struggle for Life_.

Here are two figures of speech which conspire to produce an impression more

or less erroneous. The expression "natural selection" was chosen as serving

to indicate some parallelism with artificial selection--the selection

exercised by breeders. Now selection connotes volition, and thus gives to

the thoughts of readers a wrong bias. Some increase of this bias is

produced by the words in the second title, "favoured races;" for anything

which is favoured implies the existence of some agent conferring a favour.

I do not mean that Mr. Darwin himself failed to recognize the misleading

connotations of his words, or that he did not avoid being misled by them.

In chapter iv of the _Origin of Species_, he says that, considered

literally, "natural selection is a false term," and that the

personification of Nature is objectionable; but he thinks that readers, and

those who adopt his views, will soon learn to guard themselves against the

wrong implications. Here I venture to think that he was mistaken. For

thinking this, there is the reason that even his disciple, Mr. Wallace--no,

not his disciple, but his co-discoverer, ever to be honoured--has

apparently been influenced by them. When, for example, in combating a view

of mine, he says that "the very thing said to be impossible by variation

and natural selection has been again and again effected, by variation and

artificial selection," he seems clearly to imply that the processes are

analogous, and operate in the same way. Now this is untrue. They are

analogous only within certain narrow limits; and, in the great majority of

cases, natural selection is utterly incapable of doing that which

artificial selection does.

To see this it needs only to de-personalise Nature, and to remember that,

as Mr. Darwin says, Nature is "only the aggregate action and product of

many natural laws [forces]." Observe its relative shortcomings. Artificial

selection can pick out a particular trait, and, regardless of other traits

of the individuals displaying it, can increase it by selective breeding in

successive generations. For, to the breeder or fancier, it matters little

whether such individuals are otherwise well constituted. They may be in

this or that way so unfit for carrying on the struggle for life, that were

they without human care, they would disappear forthwith. On the other hand,

if we regard Nature as that which it is, an assemblage of various forces,

inorganic and organic, some favourable to the maintenance of life and many

at variance with its maintenance--forces which operate blindly--we see that

there is no such selection of this or that trait; but that there is a

selection only of individuals which are, by the aggregate of their traits,

best fitted for living. And here I may note an advantage possessed by the

expression "survival of the fittest;" since this does not tend to raise the

thought of any one character which, more than others, is to be maintained

or increased; but tends rather to raise the thought of a general adaptation

for all purposes. It implies the process which Nature can alone carry

on--the leaving alive of those which are best able to utilize surrounding

aids to life, and best able to combat or avoid surrounding dangers. And

while this phrase covers the great mass of cases in which there are

preserved well-constituted individuals, it also covers those special cases

which are suggested by the phrase "natural selection," in which individuals

succeed beyond others in the struggle for life, by the help of particular

characters which conduce in important ways to prosperity and

multiplication. For now observe the fact which here chiefly concerns us,

that survival of the fittest can increase any serviceable trait, only if

that trait conduces to prosperity of the individual, or of posterity, or of

both, _in an important degree_. There can be no increase of any structure

by natural selection unless, amid all the slightly varying structures

constituting the organism, increase of this particular one is so

advantageous as to cause greater multiplication of the family in which it

arises than of other families. Variations which, though advantageous, fail

to do this, must disappear again. Let us take a case.

Keenness of scent in a deer, by giving early notice of approaching enemies,

subserves life so greatly that, other things equal, an individual having it

in an unusual degree is more likely than others to survive; and, among

descendants, to leave some similarly endowed or more endowed, who again

transmit the variation with, in some cases, increase. Clearly this highly

useful power may be developed by natural selection. So also, for like

reasons, may quickness of vision and delicacy of hearing; though it may be

remarked in passing that since this extra sense-endowment, serving to give

early alarm, profits the herd as a whole, which takes the alarm from one

individual, selection of it is not so easy, unless it occurs in a

conquering stag. But now suppose that one member of the herd--perhaps

because of more efficient teeth, perhaps by greater muscularity of stomach,

perhaps by secretion of more appropriate gastric juices--is enabled to eat

and digest a not uncommon plant which the others refuse. This peculiarity

may, if food is scarce, conduce to better self-maintenance, and better

fostering of young if the individual is a hind. But unless this plant is

abundant, and the advantage consequently great, the advantages which other

members of the herd gain from other slight variations may be equivalent.

This one has unusual agility, and leaps a chasm which others balk at. That

one develops longer hair in winter, and resists the cold better. Another

has a skin less irritated by flies, and can graze without so much

interruption. Here is one which has an unusual power of detecting food

under the snow; and there is one which shows extra sagacity in the choice

of a shelter from wind and rain. That the variation giving ability to eat a

plant before unutilized, may become a trait of the herd, and eventually of

a variety, it is needful that the individual in which it occurs shall have

more descendants, or better descendants, or both, than have the various

other individuals severally having their small superiorities. If these

other individuals severally profit by their small superiorities, and

transmit them to equally large numbers of offspring, no increase of the

variation in question can take place: it must soon be cancelled. Whether in

the _Origin of Species_ Mr. Darwin has recognized this fact, I do not

remember, but he has certainly done it by implication in his _Animals and

Plants under Domestication_. Speaking of variations in domestic animals, he

there says that "any particular variation would generally be lost by

crossing, reversion, and the accidental destruction of the varying

individuals, unless carefully preserved by man." (Vol. II, p. 292.) That

which survival of the fittest does in cases like the one I have instanced,

is to keep all faculties up to the mark, by destroying such individuals as

have faculties in some respect below the mark; and it can produce

development of some one faculty only if that faculty is predominantly

important. It seems to me that many naturalists have practically lost sight

of this, and assume that natural selection will increase _any_ advantageous

trait. Certainly a view now held by some assumes as much.

The consideration of this view, to which the foregoing paragraph is

introductory, may now be entered upon. This view concerns, not direct

selection, but what has been called, in questionable logic, "reversed

selection"--the selection which effects, not increase of an organ, but

decrease of it. For as, under some conditions, it is of advantage to an

individual and its descendants to have some structure of larger size, it

may be, under other conditions--namely, when the organ becomes useless--of

advantage to have it of smaller size; since, even if it is not in the way,

its weight and the cost of its nutrition are injurious taxes on the

organism. But now comes the truth to be emphasized. Just as direct

selection can increase an organ only in certain cases, so can reversed

selection decrease it only in certain cases. Like the increase produced by

a variation, the decrease produced by one must be such as will sensibly

conduce to preservation and multiplication. It is, for instance,

conceivable that were the long and massive tail of the kangaroo to become

useless (say by the forcing of the species into a mountainous and rocky

habitat filled with brushwood), a variation which considerably reduced the

tail might sensibly profit the individual in which it occurred; and, in

seasons when food was scarce, might cause survival when individuals with

large tails died. But the economy of nutrition must be considerable before

any such result could occur. Suppose that in this new habitat the kangaroo

had no enemies; and suppose that, consequently, quickness of hearing not

being called for, large ears gave no greater advantage than small ones.

Would an individual with smaller ears than usual, survive and propagate

better than other individuals, in consequence of the economy of nutrition

achieved? To suppose this is to suppose that the saving of a grain or two

of protein per day would determine the kangaroo's fate.

Long ago I discussed this matter in the _Principles of Biology_ (§ 166),

taking as an instance the decrease of the jaw implied by the crowding of

the teeth, and now proved by measurement to have taken place. Here is the

passage:--

"No functional superiority possessed by a small jaw over a large jaw, in

civilized life, can be named as having caused the more frequent survival

of small-jawed individuals. The only advantage which smallness of jaw

might be supposed to give, is the advantage of economized nutrition; and

this could not be great enough to further the preservation of men

possessing it. The decrease of weight in the jaw and co-operative parts

that has arisen in the course of many thousands of years, does not amount

to more than a few ounces. This decrease has to be divided among the many

generations that have lived and died in the interval. Let us admit that

the weight of these parts diminished to the extent of an ounce in a

single generation (which is a large admission); it still cannot be

contended that the having to carry an ounce less in weight, or having to

keep in repair an ounce less of tissue, could sensibly affect any man's

fate. And if it never did this--nay, if it did not cause a _frequent_

survival of small-jawed individuals where large-jawed individuals died,

natural selection could neither cause nor aid diminution of the jaw and

its appendages."

When writing this passage in 1864, I never dreamt that a quarter of a

century later, the supposable cause of degeneration here examined and

excluded as impossible, would be enunciated as an actual cause and named

"reversed selection."

One of the arguments used to show the adequacy of natural selection under

its direct or indirect form consists of a counter-argument to the effect

that inheritance of functionally-wrought changes, supposing it to be

operative, does not explain certain of the facts. This is alleged by Prof.

Weismann as a part justification for his doctrine of Panmixia. Concerning

the "blind fish and amphibia" found in dark places, which have but

rudimentary eyes "hidden under the skin," he argues that "it is difficult

to reconcile the facts of the case with the ordinary theory that the eyes

of these animals have simply degenerated through disuse." After giving

instances of rapid degeneration of disused organs, he argues that if "the

effects of disuse are so striking in a single life, we should certainly

expect, if such effects can be transmitted, that all traces of an eye would

soon disappear from a species which lives in the dark." Doubtless this is a

reasonable conclusion. To explain the facts on the hypothesis that acquired

characters are inheritable, seems very difficult. One possible explanation

may, indeed, be named. It appears to be a general law of organization that

structures are stable in proportion to their antiquity--that while organs

of relatively modern origin have but a comparatively superficial root in

the constitution, and readily disappear if the conditions do not favour

their maintenance, organs of ancient origin have deep-seated roots in the

constitution, and do not readily disappear. Having been early elements in

the type, and having continued to be reproduced as parts of it during a

period extending throughout many geological epochs, they are comparatively

persistent. Now the eye answers to this description as being a very early

organ. But waiving possible explanations, let us take the particular

instance cited by Prof. Weismann and see what is to be made of it. He

writes:--

"The caverns in Carniola and Carinthia, in which the blind _Proteus_ and

so many other blind animals live, belong geologically to the Jurassic

formation; and although we do not exactly know when for example the

_Proteus_ first entered them, the low organization of this amphibian

certainly indicates that it has been sheltered there for a very long

period of time, and that thousands of generations of this species have

succeeded one another in the caves.

"Hence there is no reason to wonder at the extent to which the

degeneration of the eye has been already carried in the _Proteus_; even

if we assume that it is merely due to the cessation of the conserving

influence of natural selection."[103]

Let me first note a strange oversight on the part of Prof. Weismann. He

points out that the caverns in question belong to the Jurassic formation:

apparently intending to imply that they have an antiquity related to that

of the formation. But there is no such relation, except that the caverns

cannot be older than the formation. They may have originated at any period

since the containing strata were deposited; and they may be therefore

relatively modern. But passing over this, and admitting that the _Proteus_

has inhabited the caverns for an enormous period, what is to be said of the

fact that their eyes have not disappeared entirely, as Prof. Weismann

contends they should have done had the inheritance of the effects of disuse

been all along operative? There is a very sufficient answer--the

rudimentary eyes are not entirely useless. It seems that when the

underground streams it inhabits are unusually swollen, some individuals of

the species are carried out of the caverns into the open (being then

sometimes captured). It is also said that the creatures shun the light;

this trait being, I presume, observed when it is in captivity. Now

obviously, among individuals carried out into the open, those which remain

visible are apt to be carried off by enemies; whereas, those which,

appreciating the difference between light and darkness, shelter themselves

in dark places, survive. Hence the tendency of natural selection is to

prevent the decrease of the eyes beyond that point at which they can

distinguish between light and darkness. Thus the apparent anomaly is

explained.

Let me suggest, as another possible reason for persistence of rudimentary

organs, that the principle of economy of growth will cause diminution of

them only in proportion as their constituents are of value for other uses

in the organism; and that in many cases their constituents are practically

valueless. Hence probably the reason why, in the case of stalk-eyed

crustaceans, the eye is gone but the pedicle remains, or to use Mr.

Darwin's simile, the telescope has disappeared but not its stand.

* * * * *

Along with that inadequacy of natural selection to explain changes of

structure which do not aid life in important ways, alleged in § 166 of _The

Principles of Biology_, a further inadequacy was alleged. It was contended

that the relative powers of co-operative parts cannot be adjusted solely by

survival of the fittest; and especially where the parts are numerous and

the co-operation complex. In illustration it was pointed out that immensely

developed horns, such as those of the extinct Irish elk, weighing over a

hundred-weight, could not, with the massive skull bearing them, be carried

at the extremity of the outstretched neck without many and great

modifications of adjacent bones and muscles of the neck and thorax; and

that without strengthening of the fore-legs, too, there would be failure

alike in fighting and in locomotion. And it was argued that while we cannot

assume spontaneous increase of all these parts proportionate to the

additional strains, we cannot suppose them to increase by variations, one

at once, without supposing the creature to be disadvantaged by the weight

and nutrition of parts that were for the time useless--parts, moreover,

which would revert to their original sizes before the other needful

variations occurred.

When, in reply to me, it was contended that co-operative parts vary

together, I named facts conflicting with this assertion--the fact that the

blind cray-fish of the Kentucky caves have lost their eyes but not the

foot-stalks carrying them; the fact that the normal proportion between

tongue and beak in certain selected varieties of pigeons is lost; the fact

that lack of concomitance in decrease of jaws and teeth in sundry kinds of

pet dogs, has caused great crowding of the teeth ("The Factors of Organic

Evolution," _Essays_, i, 401-402). And I then argued that if co-operative

parts, small in number and so closely associated as these are, do not vary

together, it is unwarrantable to allege that co-operative parts which are

very numerous and remote from one another vary together. After making this

rejoinder I enforced my argument by a further example--that of the giraffe.

Tacitly recognizing the truth that the unusual structure of this creature

must have been, in its most conspicuous traits, the result of survival of

the fittest (since it is absurd to suppose that efforts to reach high

branches could lengthen the legs), I illustrated afresh the obstacles to

co-adaptation. Not dwelling on the objection that increase of any

components of the fore-quarters out of adjustment to the others, would

cause evil rather than good, I went on to argue that the co-adaptation of

parts required to make the giraffe's structure useful, is much greater than

at first appears. This animal has a grotesque gallop, necessitated by the

great difference in length between the fore and the hind limbs. I pointed

out that the mode of action of the hind limbs shows that the bones and

muscles have all been changed in their proportions and adjustments; and I

contended that, difficult as it is to believe that all parts of the

fore-quarters have been co-adapted by the appropriate variations, now of

this part now of that, it becomes impossible to believe that all the parts

in the hind-quarters have been simultaneously co-adapted to one another and

to all the parts of the fore-quarters: adding that want of co-adaptation,

even in a single muscle, would cause fatal results when high speed had to

be maintained while escaping from an enemy.

Since this argument, repeated with this fresh illustration, was published

in 1886, I have met with nothing to be called a reply; and might, I think,

if convictions usually followed proofs, leave the matter as it stands. It

is true that, in his _Darwinism_, Mr. Wallace has adverted to my renewed

objection, and, as already said, contended that changes such as those

instanced can be effected by natural selection, since such changes can be

effected by artificial selection: a contention which, as I have pointed

out, assumes a parallelism that does not exist. But now, instead of

pursuing the argument further along the same line, let me take a somewhat

different line.

If there occurs some change in an organ, say by increase of its size, which

adapts it better to the creature's needs, it is admitted that when, as

commonly happens, the use of the organ demands the co-operation of other

organs, the change in it will generally be of no service unless the

co-operative organs are changed. If, for instance, there takes place such a

modification of a rodent's tail as that which, by successive increases,

produces the trowel-shaped tail of the beaver, no advantage will be derived

unless there also take place certain modifications in the bulks and shapes

of the adjacent vertebræ and their attached muscles, as well as, probably,

in the hind limbs; enabling them to withstand the reactions of the blows

given by the tail. And the question is, by what process these many parts,

changed in different degrees, are co-adapted to the new

requirements--whether variation and natural selection alone can effect the

readjustment. There are three conceivable ways in which the parts may

simultaneously change:--(1) they may all increase or decrease together in

like degree; (2) they may all simultaneously increase or decrease

independently, so as not to maintain their previous proportions, or assume

any other special proportions; (3) they may vary in such ways and degrees

as to make them jointly serviceable for the new end. Let us consider

closely these several conceivabilities.

And first of all, what are we to understand by co-operative parts? In a

general sense, all the organs of the body are co-operative parts, and are

respectively liable to be more or less changed by change in any one. In a

narrower sense, more directly relevant to the argument, we may, if we

choose to multiply difficulties, take the entire framework of bones and

muscles as formed of co-operative parts; for these are so related that any

considerable change in the actions of some entails change in the actions of

most others. It needs only to observe how, when putting out an effort,

there goes, along with a deep breath, an expansion of the chest and a

bracing up of the abdomen, to see that various muscles beyond those

directly concerned are strained along with them. Or, when suffering from

lumbago, an effort to lift a chair will cause an acute consciousness that

not the arms only are brought into action, but also the muscles of the

back. These cases show how the motor organs are so tied together that

altered actions of some implicate others quite remote from them.

But without using the advantage which this interpretation of the words

would give, let us take, as co-operative organs, those which are obviously

such--the organs of locomotion. What, then, shall we say of the fore limbs

and hind limbs of terrestrial mammals, which co-operate closely and

perpetually? Do they vary together? If so, how have there been produced

such contrasted structures as that of the kangaroo, with its large hind

limbs and small fore limbs, and that of the giraffe, in which the hind

limbs are small and the fore limbs large--how does it happen that,

descending from the same primitive mammal, these creatures have diverged in

the proportions of their limbs in opposite directions? Take, again, the

articulate animals. Compare one of the lower types, with its rows of almost

equal-sized limbs, and one of the higher types, as a crab or a lobster,

with limbs some very small and some very large. How came this contrast to

arise in the course of evolution, if there was the equality of variation

supposed?

But now let us narrow the meaning of the phrase still further, giving it a

more favourable interpretation. Instead of considering separate limbs as

co-operative, let us consider the component parts of the same limb as

co-operative, and ask what would result, from varying together. It would in

that case happen that, though the fore and hind limbs of a mammal might

become different in their sizes, they would not become different in their

structures. If so, how have there arisen the unlikenesses between the hind

legs of the kangaroo and those of the elephant? Or if this comparison is

objected to, because the creatures belong to the widely different divisions

of implacental and placental mammals, take the cases of the rabbit and the

elephant, both belonging to the last division. On the hypothesis of

evolution these are both derived from the same original form; but the

proportions of the parts have become so widely unlike that the

corresponding joints are scarcely recognized as such by the unobservant: at

what seem corresponding places the legs bend in opposite ways. Equally

marked, or more marked, is the parallel fact among the _Articulata_. Take

that limb of the lobster which bears the claw and compare it with the

corresponding limb in an inferior articulate animal, or the corresponding

limb of its near ally, the rock lobster, and it becomes obvious that the

component segments of the limb have come to bear to one another in the one

case, proportions immensely different from those they bear in the other

case. Undeniably, then, on contemplating the general facts of organic

structure, we see that the concomitant variations in the parts of limbs,

have not been of a kind to produce equal amounts of change in them, but

quite the opposite--have been everywhere producing inequalities. Moreover,

we are reminded that this production of inequalities among co-operative

parts, is an essential principle of development. Had it not been so, there

could not have been that progress from homogeneity of structure to

heterogeneity of structure which constitutes evolution.

We pass now to the second supposition:--that the variations in co-operative

parts occur irregularly, or in such independent ways that they bear no

definite relations to one another--miscellaneously, let us say. This is the

supposition which best corresponds with the facts. Glances at the faces

around yield conspicuous proofs. Many of the muscles of the face and some

of the bones, are distinctly co-operative; and these respectively vary in

such ways as to produce in each person a different combination. What we see

in the face we have reason to believe holds in the limbs and in all other

parts. Indeed, it needs but to compare people whose arms are of the same

lengths, and observe how stumpy are the fingers of one and how slender

those of another; or it needs but to note the unlikenesses of gait of

passers-by, implying small unlikenesses of structure; to be convinced that

the relations among the variations of co-operative parts are anything but

fixed. And now, confining our attention to limbs, let us consider what must

happen if, by variations taking place miscellaneously, limbs have to be

partially changed from fitness for one function to fitness for another

function--have to be re-adapted. That the reader may fully comprehend the

argument, he must here have patience while a good many anatomical details

are set down.

Let us suppose a species of quadruped of which the members have, for

immense past periods, been accustomed to locomotion over a relatively even

surface, as, for instance, the "prairie-dogs" of North America; and let us

suppose that increase of numbers has driven part of them into a region full

of obstacles to easy locomotion--covered, say, by the decaying stems of

fallen trees, such as one sees in portions of primeval forest. Ability to

leap must then become a useful trait; and, according to the hypothesis we

are considering, this ability will be produced by the selection of

favourable variations. What are the variations required? A leap is effected

chiefly by the bending of the hind limbs so as to make sharp angles at the

joints, and then suddenly straightening them; as any one may see on

watching a cat leap on to the table. The first required change, then, is

increase of the large extensor muscles, by which the hind limbs are

straightened. Their increases must be duly proportioned; for if those which

straightened one joint become much stronger than those which straightened

the other joint, the result must be collapse of the other joint when the

muscles are contracted together. But let us make a large admission, and

suppose these muscles to vary together; what further muscular change is

next required? In a plantigrade mammal the metatarsal bones chiefly bear

the reaction of the leap, though the toes may have a share. In a

digitigrade mammal, however, the toes form almost exclusively the fulcrum,

and if they are to bear the reaction of a higher leap, the flexor muscles

which depress and bend them must be proportionately enlarged: if not, the

leap will fail from want of a firm _point d'appui_. Tendons as well as

muscles must be modified; and, among others, the many tendons which go to

the digits and their phalanges. Stronger muscles and tendons imply greater

strains on the joints; and unless these are strengthened, one or other,

dislocation will be caused by a more vigorous spring. Not only the

articulations themselves must be so modified as to bear greater stress, but

also the numerous ligaments which hold the parts of each in place. Nor can

the bodies of the bones remain unstrengthened; for if they have no more

than the strengths needed for previous movements they will fail to bear

more violent movements. Thus, saying nothing of the required changes in the

pelvis, as well as in the nerves and blood-vessels, there are, counting

bones, muscles, tendons, ligaments, at least fifty different parts in each

hind leg which have to be enlarged. Moreover they have to be enlarged in

unlike degrees. The muscles and tendons of the outer toes, for example,

need not be added to so much as those of the median toes. Now, throughout

their successive stages of growth, all these parts have to be kept fairly

well balanced; as any one may infer on remembering sundry of the accidents

he has known. Among my own friends I could name one who, when playing

lawn-tennis, snapped the Achilles tendon; another who, while swinging his

children, tore some of the muscular fibres in the calf of his leg; another

who, in getting over a fence, tore a ligament of one knee. Such facts,

joined with every one's experience of sprains, show that during the extreme

exertions to which limbs are now and then subject, there is a giving way of

parts not quite up to the required level of strength. How, then, is this

balance to be maintained? Suppose the extensor muscles have all varied

appropriately; their variations are useless unless the other co-operative

parts have also varied appropriately. Worse than this. Saying nothing of

the disadvantage caused by extra weight and cost of nutrition, they will be

causes of mischief--causes of derangement to the rest by contracting with

undue force. And then, how long will it take for the rest to be brought

into adjustment? As Mr. Darwin says concerning domestic animals:--"Any

particular variation would generally be lost by crossing, reversion, &c.

... unless carefully preserved by man." In a state of nature, then,

favourable variations of these muscles would disappear again long before

one or a few of the co-operative parts could be appropriately varied, much

more before all of them could.

With this insurmountable difficulty goes a difficulty still more

insurmountable--if the expression may be allowed. It is not a question of

increased sizes of parts only, but of altered shapes of parts, too. A

glance at the skeletons of mammals shows how unlike are the forms of the

corresponding bones of their limbs; and shows that they have been severally

re-moulded in each species to the different requirements entailed by its

different habits. The change from the structures of hind limbs fitted only

for walking and trotting to hind limbs fitted also for leaping, implies,

therefore, that, along with strengthenings of bones there must go

alterations in their forms. Now the fortuitous alterations of form which

may take place in any bone are countless. How long, then, will it be before

there takes place that particular alteration which will make the bone

fitter for its new action? And what is the probability that the many

required changes of shape, as well as of size, in bones will each of them

be effected before all the others are lost again? If the probabilities

against success are incalculable, when we take account only of changes in

the sizes of parts, what shall we say of their incalculableness when

differences of form also are taken into account?

"Surely this piling up of difficulties has gone far enough"; the reader

will be inclined to say. By no means. There is a difficulty immeasurably

transcending those named. We have thus far omitted the second half of the

leap, and the provisions to be made for it. After ascent of the animal's

body comes descent; and the greater the force with which it is projected

up, the greater is the force with which it comes down. Hence, if the

supposed creature has undergone such changes in the hind limbs as will

enable them to propel it to a greater height, without having undergone any

changes in the fore limbs, the result will be that on its descent the fore

limbs will give way, and it will come down on its nose. The fore limbs,

then, have to be changed simultaneously with the hind. How changed?

Contrast the markedly bent hind limbs of a cat with its almost straight

fore limbs, or contrast the silence of the spring on to the table with the

thud which the fore paws make as it jumps off the table. See how unlike the

actions of the hind and fore limbs are, and how unlike their structures. In

what way, then, is the required co-adaptation to be effected? Even were it

a question of relative sizes only, there would be no answer; for facts

already given show that we may not assume simultaneous increases of size to

take place in the hind and fore limbs; and, indeed, a glance at the various

human races, which differ considerably in the ratios of their legs to their

arms, shows us this. But it is not simply a question of sizes. To bear the

increased shock of descent the fore limbs must be changed throughout in

their structures. Like those in the hind limbs, the changes must be of many

parts in many proportions; and they must be both in sizes and in shapes.

More than this. The scapular arch and its attached muscles must also be

strengthened and re-moulded. See, then, the total requirements. We must

suppose that by natural selection of miscellaneous variations, the parts of

the hind limbs will be co-adapted to one another, in sizes, shapes, and

ratios; that those of the fore limbs will undergo co-adaptation similar in

their complexity, but dissimilar in their kinds; and that the two sets of

co-adaptations will be effected _pari passu_. If, as may be held, the

probabilities are millions to one against the first set of changes being

achieved, then it may be held that the probabilities are billions to one

against the second being simultaneously achieved, in progressive adjustment

to the first.

There remains only to notice the third conceivable mode of adjustment. It

may be imagined that though, by the natural selection of miscellaneous

variations, these adjustments cannot be effected, they may nevertheless be

made to take place appropriately. How made? To suppose them so made is to

suppose that the prescribed end is somewhere recognized; and that the

changes are step by step simultaneously proportioned for achieving it--is

to suppose a designed production of these changes. In such case, then, we

have to fall back in part upon the primitive hypothesis; and if we do this

in part, we may as well do it wholly--may as well avowedly return to the

doctrine of special creations.

What, then, is the only defensible interpretation? If such modifications of

structure produced by modifications of function as we see take place in

each individual, are in any measure transmissible to descendants, then all

these co-adaptations, from the simplest up to the most complex, are

accounted for. In some cases this inheritance of acquired characters

suffices by itself to explain the facts; and in other cases it suffices

when taken in combination with the selection of favourable variations. An

example of the first class is furnished by the change just considered; and

an example of the second class is furnished by the case, before named, of

development in a deer's horns. If, by some extra massiveness spontaneously

arising, or by formation of an additional "point," an advantage is gained

either for attack or defence, then, if the increased muscularity and

strengthened structure of the neck and thorax, which wielding of these

somewhat heavier horns produces, are in a greater or less degree inherited,

and in several successive generations are by this process brought up to the

required extra strength, it becomes possible and advantageous for a further

increase of the horns to take place, and a further increase in the

apparatus for wielding them, and so on continuously. By such processes

only, in which each part gains strength in proportion to function, can

co-operative parts be kept in adjustment, and be re-adjusted to meet new

requirements. Close contemplation of the facts impresses me more strongly

than ever with the two alternatives--either there has been inheritance of

acquired characters, or there has been no evolution.

This very pronounced opinion will be met, on the part of some, by a no less

pronounced demurrer, which involves a denial of possibility. It has been of

late asserted, and by many believed, that inheritance of acquired

characters cannot occur. Weismann, they say, has shown that there is early

established in the evolution of each organism such a distinctness between

those component units which carry on the individual life and those which

are devoted to maintenance of the species, that changes in the one cannot

affect the other. We will look closely into his doctrine.

Basing his argument on the principle of the physiological division of

labour, and assuming that the primary division of labour is that between

such part of an organism as carries on individual life and such part as is

reserved for the production of other lives, Weismann, starting with "the

first multicellular organism," says that--"Hence the single group would

come to be divided into two groups of cells, which may be called somatic

and reproductive--the cells of the body as opposed to those which are

concerned with reproduction." (_Essays upon Heredity_, i, p. 27.)

Though he admits that this differentiation "was not at first absolute, and

indeed is not always so to-day," yet he holds that the differentiation

eventually becomes absolute in the sense that the somatic cells, or those

which compose the body at large, come to have only a limited power of

cell-division, instead of an unlimited power which the reproductive cells

have; and also in the sense that eventually there ceases to be any

communication between the two further than that implied by the supplying of

nutriment to the reproductive cells by the somatic cells. The outcome of

this argument is that, in the absence of communication, changes induced in

the somatic cells, constituting the individual, cannot influence the

natures of the reproductive cells, and cannot therefore be transmitted to

posterity. Such is the theory. Now let us look at a few facts--some

familiar, some unfamiliar.

His investigations led Pasteur to the positive conclusion that the silkworm

diseases are inherited. The transmission from parent to offspring resulted,

not through any contamination of the surface of the egg by the body of the

parent while being deposited, but resulted from infection of the egg

itself--intrusion of the parasitic organism. Generalized observations

concerning the disease called _pébrine_, enabled him to decide, by

inspection of the eggs, which were infected and which were not: certain

modifications of form distinguishing the diseased ones. More than this; the

infection was proved by microscopical examination of the contents of the

egg; in proof of which he quotes as follows from Dr. Carlo Vittadini:--

"Il résulte de mes recherches sur les graines, à l'époque où commence le

développement du germe, que les corpuscules, une fois apparus dans

l'oeuf, augmentent graduellement en nombre, à mesure que l'embryon se

développe; que, dans les derniers jours de l'incubation, l'oeuf en est

plein, au point de faire croire que la majeure partie des granules du

jaune se sont transformés en corpuscules.

"Une autre observation importante est que l'embryon aussi est souillé de

corpuscules, et à un degré tel qu'on peut soupçonner que l'infection du

jaune tire son origine du germe lui-même; en d'autres termes que le germe

est primordialement infecté, et porte en lui-même ces corpuscules tout

comme les vers adultes, frappés du même mal."[104]

Thus, then the substance of the egg and even its innermost vital part, is

permeable by a parasite sufficiently large to be microscopically visible.

It is also of course permeable by the invisible molecules of protein, out

of which its living tissues are formed, and by absorption of which they

subsequently grow. But, according to Weismann, it is _not_ permeable by

those invisible units of protoplasm out of which the vitally active tissues

of the parent are constituted: units composed, as we must assume, of

variously arranged molecules of protein. So that the big thing may pass,

and the little thing may pass, but the intermediate thing may not pass!

A fact of kindred nature, unhappily more familiar, may be next brought in

evidence. It concerns the transmission of a disease not infrequent among

those of unregulated lives. The highest authority concerning this disease,

in its inherited form, is Mr. Jonathan Hutchinson; and the following are

extracts from a letter I have received from him, and which I publish with

his assent:--

"I do not think that there can be any reasonable doubt that a very large

majority of those who suffer from inherited syphilis take the taint from

the male parent.... It is the rule when a man marries who has no

remaining local lesion, but in whom the taint is not eradicated, for his

wife to remain apparently well, whilst her child may suffer. No doubt the

child infects its mother's blood, but this does not usually evoke any

obvious symptoms of syphilis.... I am sure I have seen hundreds of

syphilitic infants whose mothers had not, so far as I could ascertain,

ever displayed a single symptom."

See, then, to what we are committed if we accept Weismann's hypothesis. We

must conclude, that whereas the reproductive cell may be effectually

invaded by an abnormal living element in the parental organism, those

normal living elements which constitute the vital protoplasm of the

parental organism, cannot invade it. Or if it be admitted that both

intrude, then the implication is that, whereas the abnormal element can so

modify the development as to cause changes of structure (as of the teeth),

the normal element can cause no changes of structure![105]

We pass now to evidence not much known to the world at large, but widely

known in the biological world, though known in so incomplete a manner as to

be undervalued in it. Indeed, when I name it, probably many will vent a

mental pooh-pooh. The fact to which I refer is one of which record is

preserved in the museum of the College of Surgeons, in the shape of

paintings of a foal borne by a mare not quite thoroughbred, to a sire which

was thoroughbred--a foal which bears the markings of the quagga. The

history of this remarkable foal is given by the Earl of Morton, F.R.S., in

a letter to the President of the Royal Society (read November 23, 1820). In

it he states that wishing to domesticate the quagga, and having obtained a

male but not a female, he made an experiment.

"I tried to breed from the male quagga and a young chestnut mare of

seven-eighths Arabian blood, and which had never been bred from; the

result was the production of a female hybrid, now five years old, and

bearing, both in her form and in her colour, very decided indications of

her mixed origin. I subsequently parted with the seven-eighths Arabian

mare to Sir Gore Ouseley, who has bred from her by a very fine black

Arabian horse. I yesterday morning examined the produce, namely, a

two-year-old filly and a year-old colt. They have the character of the

Arabian breed as decidedly as can be expected, where fifteen-sixteenths

of the blood are Arabian; and they are fine specimens of that breed; but

both in their colour and in the hair of their manes, they have a striking

resemblance to the quagga. Their colour is bay, marked more or less like

the quagga in a darker tint. Both are distinguished by the dark line

along the ridge of the back, the dark stripes across the forehead, and

the dark bars across the back part of the legs."[106]

Lord Morton then names sundry further correspondences. Dr. Wollaston, at

that time President of the Royal Society, who had seen the animals,

testified to the correctness of his description, and, as shown by his

remarks, entertained no doubt about the alleged facts. But good reason for

doubt may be assigned. There naturally arises the question--How does it

happen that parallel results are not observed in other cases? If in any

progeny certain traits not belonging to the sire, but belonging to a sire

of preceding progeny, are reproduced, how is it that such anomalously

inherited traits are not observed in domestic animals, and indeed in

mankind? How is it that the children of a widow by a second husband do not

bear traceable resemblances to the first husband? To these questions

nothing like satisfactory replies seem forthcoming; and, in the absence of

replies, scepticism, if not disbelief, may be held reasonable.

There is an explanation, however. Forty years ago I made acquaintance with

a fact which impressed me by its significant implications, and has, for

this reason I suppose, remained in my memory. It is set forth in the

_Journal of the Royal Agricultural Society_, Vol. XIV (1853), pp. 214 _et

seq._, and concerns certain results of crossing French and English breeds

of sheep. The writer of the translated paper, M. Malingie-Nouel, Director

of the Agricultural School of La Charmoise, states that when the French

breeds of sheep (in which were included "the _mongrel_ Merinos") were

crossed with an English breed, "the lambs present the following results.

Most of them resemble the mother more than the father; some show no trace

of the father." Joining the admission respecting the mongrels with the

facts subsequently stated, it is tolerably clear that the cases in which

the lambs bore no traces of the father were cases in which the mother was

of pure breed. Speaking of the results of these crossings in the second

generation, "having 75 per cent. of English blood," M. Nouel says:--"The

lambs thrive, wear a beautiful appearance, and complete the joy of the

breeder.... No sooner are the lambs weaned than their strength, their

vigour, and their beauty begin to decay.... At last the constitution gives

way ... he remains stunted for life:" the constitution being thus proved

unstable or unadapted to the requirements. How, then, did M. Nouel succeed

in obtaining a desirable combination of a fine English breed with the

relatively poor French breeds?

He took an animal from "flocks originally sprung from a mixture of the

two distinct races that are established in those two provinces [Berry and

La Sologne]," and these he "united with animals of another mixed breed

... which blended the Tourangelle and native Merino blood of" La Beauce

and Touraine, and obtained a mixture of all four races "without decided

character, without fixity ... but possessing the advantage of being used

to our climate and management."

Putting one of these "mixed blood ewes to a pure New-Kent ram ... one

obtains a lamb containing fifty-hundredths of the purest and most ancient

English blood, with twelve and a half hundredths of four different French

races, which are individually lost in the preponderance of English blood,

and disappear almost entirely, leaving the improving type in the

ascendant.... All the lambs produced strikingly resembled each other, and

even Englishmen took them for animals of their own country."

M. Nouel goes on to remark that when this derived breed was bred with

itself, the marks of the French breeds were lost. "Some slight traces"

could be detected by experts, but these "soon disappeared."

Thus we get proof that relatively pure constitutions predominate in progeny

over much mixed constitutions. The reason is not difficult to see. Every

organism tends to become adapted to its conditions of life; and all the

structures of a species, accustomed through multitudinous generations to

the climate, food, and various influences of its locality, are moulded into

harmonious co-operation favourable to life in that locality: the result

being that in the development of each young individual, the tendencies

conspire to produce the fit organization. It is otherwise when the species

is removed to a habitat of different character, or when it is of mixed

breed. In the one case its organs, partially out of harmony with the

requirements of its new life, become partially out of harmony with one

another; since, while one influence, say of climate, is but little changed,

another influence, say of food, is much changed; and, consequently, the

perturbed relations of the organs interfere with their original stable

equilibrium. Still more in the other case is there a disturbance in

equilibrium. In a mongrel, the constitution derived from each source

repeats itself as far as possible. Hence a conflict of tendencies to evolve

two structures more or less unlike. The tendencies do not harmoniously

conspire, but produce partially incongruous sets of organs. And evidently

where the breed is one in which there are united the traits of various

lines of ancestry, there results an organization so full of small

incongruities of structure and action, that it has a much-diminished power

of maintaining its balance; and while it cannot withstand so well adverse

influences, it cannot so well hold its own in the offspring. Concerning

parents of pure and mixed breeds respectively, severally tending to

reproduce their own structures in progeny, we may therefore say,

figuratively, that the house divided against itself cannot withstand the

house of which the members are in concord.

Now if this is shown to be the case with breeds the purest of which have

been adapted to their habitats and modes of life during some few hundred

years only, what shall we say when the question is of a breed which has had

a constant mode of life in the same locality for ten thousand years or

more, like the quagga? In this the stability of constitution must be such

as no domestic animal can approach. Relatively stable as may have been the

constitutions of Lord Morton's horses, as compared with the constitutions

of ordinary horses, yet, since Arab horses, even in their native country,

have probably in the course of successive conquests and migrations of

tribes become more or less mixed, and since they have been subject to the

conditions of domestic life, differing much from the conditions of their

original wild life, and since the English breed has undergone the

perturbing effects of change from the climate and food of the East to the

climate and food of the West, the organizations of the horse and mare in

question could have had nothing like that perfect balance produced in the

quagga by a hundred centuries of harmonious co-operation. Hence the result.

And hence at the same time the interpretation of the fact that analogous

phenomena are not obvious among most domestic animals, or among ourselves;

since both have relatively mixed, and generally extremely mixed,

constitutions, which, as we see in ourselves, have been made generation

after generation, not by the formation of a mean between two parents, but

by the jumbling of traits of the one with traits of the other; until there

exist no such conspiring tendencies among the parts as cause repetition of

combined details of structure in posterity.

Expectation that scepticism might be felt respecting this alleged anomaly

presented by the quagga-marked foal, had led me to think over the matter;

and I had reached this interpretation before sending to the College of

Surgeons Museum (being unable to go myself) to obtain the particulars and

refer to the records. When there was brought to me a copy of the account as

set forth in the _Philosophical Transactions_, it was joined with the

information that there existed an appended account of pigs, in which a

parallel fact had been observed. To my immediate inquiry--"Was the male a

wild pig?" there came the reply--"I did not observe." Of course I forthwith

obtained the volume, and there found what I expected. It was contained in a

paper communicated by Dr. Wollaston from Daniel Giles, Esq., concerning his

"sow and her produce," which said that--

"she was one of a well-known black and white breed of Mr. Western, the

Member for Essex. About ten years since I put her to a boar of the wild

breed, and of a deep chestnut colour which I had just received from

Hatfield House, and which was soon afterwards drowned by accident. The

pigs produced (which were her first litter) partook in appearance of both

boar and sow, but in some the chestnut colour of the boar strongly

prevailed.

"The sow was afterwards put to a boar of Mr. Western's breed (the wild

boar having been long dead). The produce was a litter of pigs, some of

which, we observed with much surprise, to be stained and clearly marked

with the chestnut colour which had prevailed in the former litter."

Mr. Giles adds that in a second litter of pigs, the father of which was of

Mr. Western's breed, he and his bailiff believe there was a recurrence, in

some, of the chestnut colour, but admits that their "recollection is much

less perfect than I wish it to be." He also adds that, in the course of

many years' experience, he had never known the least appearance of the

chestnut colour in Mr. Western's breed.

What are the probabilities that these two anomalous results should have

arisen, under these exceptional conditions, as a matter of chance?

Evidently the probabilities against such a coincidence are enormous. The

testimony is in both cases so good that, even apart from the coincidence,

it would be unreasonable to reject it; but the coincidence makes acceptance

of it imperative. There is mutual verification, at the same time that there

is a joint interpretation yielded of the strange phenomenon, and of its

non-occurrence under ordinary circumstances.

And now, in presence of these facts, what are we to say? Simply that they

are fatal to Weismann's hypothesis. They show that there is none of the

alleged independence of the reproductive cells; but that the two sets of

cells are in close communion. They prove that while the reproductive cells

multiply and arrange themselves during the evolution of the embryo, some of

their germ-plasm passes into the mass of somatic cells constituting the

parental body, and becomes a permanent component of it. Further, they

necessitate the inference that this introduced germ-plasm, everywhere

diffused, is some of it included in the reproductive cells subsequently

formed. And if we thus get a demonstration that the somewhat different

units of a foreign germ-plasm permeating the organism, permeate also the

subsequently formed reproductive cells, and affect the structures of the

individuals arising from them, the implication is that the like happens

with those native units which have been made somewhat different by modified

functions: there must be a tendency to inheritance of acquired characters.

One more step only has to be taken. It remains to ask what is the flaw in

the assumption with which Weismann's theory sets out. If, as we see, the

conclusions drawn from it do not correspond to the facts, then, either the

reasoning is invalid, or the original postulate is untrue. Leaving aside

all questions concerning the reasoning, it will suffice here to show the

untruth of the postulate. Had his work been written during the early years

of the cell-doctrine, the supposition that the multiplying cells of which

the _Metazoa_ and _Metaphyta_ are composed, become completely separate,

could not have been met by a reasonable scepticism; but now, not only is

scepticism justifiable, but denial is called for. Some dozen years ago it

was discovered that in many cases vegetal cells are connected with one

another by threads of protoplasm--threads which unite the internal

protoplasm of one cell with the internal protoplasms of cells around It is

as though the pseudopodia of imprisoned rhizopods were fused with the

pseudopodia of adjacent imprisoned rhizopods. We cannot reasonably suppose

that the continuous network of protoplasm thus constituted has been

produced after the cells have become adult. These protoplasmic connections

must have survived the process of fission. The implication is that the

cells forming the embryo-plant retained their protoplasmic connections

while they multiplied, and that such connections continued throughout all

subsequent multiplications--an implication which has, I believe, been

established by researches upon germinating palm-seeds. But now we come to a

verifying series of facts which the cell-structures of animals in their

early stages present. In his _Monograph of the Development of Peripatus

Capensis_, Mr. Adam Sedgwick, F.R.S., Reader in Animal Morphology at

Cambridge, writes as follows:--

"All the cells of the ovum, ectodermal as well as endodermal, are

connected together by a fine protoplasmic reticulum." (p. 41)

"The continuity of the various cells of the segmenting ovum is primary,

and not secondary; _i. e._, in the cleavage the segments do not

completely separate from one another. But are we justified in speaking of

cells at all in this case? _The fully segmented ovum is a syncytium, and

there are not and have not been at any stage cell limits._" (p. 41)

"It is becoming more and more clear every day that the cells composing

the tissues of animals are not isolated units, but that they are

connected with one another. I need only refer to the connection known to

exist between connective tissue cells, cartilage cells, epithelial cells,

&c. And not only may the cells of one tissue be continuous with each

other, but they may also be continuous with the cells of other tissues."

(pp. 47-8)

"Finally, if the protoplasm of the body is primitively a syncytium, and

the ovum until maturity a part of that syncytium, the separation of the

generative products does not differ essentially from the internal

gemmation of a Protozoon, and the inheritance by the offspring of

peculiarities first appearing in the parent, though not explained, is

rendered less mysterious; for the protoplasm of the whole body being

continuous, change in the molecular constitution of any part of it would

naturally be expected to spread, in time, through the whole mass." (p.

49)

Mr. Sedgwick's subsequent investigations confirm these conclusions. In a

letter of December 27, 1892, passages which he allows me to publish run as

follows:--

"All the embryological studies that I have made since that to which you

refer confirm me more and more in the view that the connections between

the cells of adults are not secondary connections, but primary, dating

from the time when the embryo was a unicellular structure.... My own

investigations on this subject have been confined to the Arthropoda,

Elasmobranchii, and Aves. I have thoroughly examined the development of

at least one kind of each of these groups, and I have never been able to

detect a stage in which the cells were not continuous with each other;

and I have studied innumerable stages from the beginning of cleavage

onwards."

So that the alleged independence of the reproductive cells does not exist.

The _soma_--to use Weismann's name for the aggregate of cells forming the

body--is, in the words of Mr. Sedgwick, "a continuous mass of vacuolated

protoplasm;" and the reproductive cells are nothing more than portions of

it separated some little time before they are required to perform their

functions.

Thus the theory of Weismann is doubly disproved. Inductively we are shown

that there _does_ take place that communication of characters from the

somatic cells to the reproductive cells, which he says cannot take place;

and deductively we are shown that this communication is a natural sequence

of connections between the two which he ignores; his various conclusions

are deduced from a postulate which is untrue.

* * * * *

From the title of this essay, and from much of its contents, nine readers

out of ten will infer that it is directed against the views of Mr. Darwin.

They will be astonished on being told that, contrariwise, it is directed

against the views of those who, in a considerable measure, dissent from Mr.

Darwin. For the inheritance of acquired characters, which it is now the

fashion in the biological world to deny, was, by Mr. Darwin, fully

recognized and often insisted on. Such of the foregoing arguments as touch

Mr. Darwin's views, simply imply that the cause of evolution which at first

he thought unimportant, but the importance of which he increasingly

perceived as he grew older, is more important than he admitted, even at the

last. The neo-Darwinists, however, do not admit this cause at all.

Let it not be supposed that this explanation implies any disapproval of the

dissentients, considered as such. Seeing how little regard for authority I

have myself usually shown, it would be absurd in me to reflect in any

degree upon those who have rejected certain of Mr. Darwin's teachings, for

reasons which they have held sufficient. But while their independence of

thought is to be applauded rather than blamed, it is, I think, to be

regretted that they have not guarded themselves against a long-standing

bias. It is a common trait of human nature to seek some excuse when found

in the wrong. Invaded self-esteem sets up a defence, and anything is made

to serve. Thus it happened that when geologists and biologists, previously

holding that all kinds of organisms arose by special creations, surrendered

to the battery opened upon them by _The Origin of Species_, they sought to

minimise their irrationality by pointing to irrationality on the other

side. "Well, at any rate, Lamarck was in the wrong." "It is clear that we

were right in rejecting _his_ doctrine." And so, by duly emphasizing the

fact that he overlooked "Natural Selection" as the chief cause, and by

showing how erroneous were some of his interpretations, they succeeded in

mitigating the sense of their own error. It is true their creed was that at

successive periods in the Earth's history, old Floras and Faunas had been

abolished and others introduced; just as though, to use Professor Huxley's

figure, the table had been now and again kicked over and a new pack of

cards brought out. And it is true that Lamarck, while he rejected this

absurd creed, assigned for the facts reasons some of which are absurd. But

in consequence of the feeling described, his defensible belief was

forgotten and only his indefensible ones remembered. This one-sided

estimate has become traditional; so that there is now often shown a subdued

contempt for those who suppose that there can be any truth in the

reasonings of a man whose general conception was partly sense, at a time

when the general conceptions of his contemporaries were wholly nonsense.

Hence results unfair treatment--hence result the different dealings with

the views of Lamarck and of Weismann.

"Where are the facts proving the inheritance of acquired characters?" ask

those who deny it. Well, in the first place, there might be asked the

counter-question--Where are the facts which disprove it? Surely if not only

the general structures of organisms, but also many of the modifications

arising in them, are inheritable, the natural implication is that all

modifications are inheritable; and if any say that the inheritableness is

limited to those arising in a certain way, the _onus_ lies on them of

proving that those otherwise arising are not inheritable.[107] Leaving this

counter-question aside, however, it will suffice if we ask another

counter-question. It is asserted that the dwindling of organs from disuse

is due to the successive survivals in posterity of individuals in which the

organs have varied in the direction of decrease. Where now are the facts

supporting this assertion? Not one has been assigned or can be assigned.

Not a single case can be named in which _panmixia_ is a proved cause of

diminution. Even had the deductive argument for _panmixia_ been as valid as

we have found it to be invalid, there would still have been required, in

pursuance of scientific method, some verifying inductive evidence. Yet,

though not a shred of such evidence has been given, the doctrine is

accepted with acclamation, and adopted as part of current biological

theory. Articles are written and letters published in which it is assumed

that this mere speculation, justified by not a tittle of proof, displaces

large conclusions previously drawn. And then, passing into the outer world,

this unsupported belief affects opinions there too; so that we have

recently had a Right Honourable lecturer who, taking for granted its truth,

represents the inheritance of acquired characters as an exploded

hypothesis, and proceeds to give revised views of human affairs.

Finally, there comes the reply that there _are_ facts proving the

inheritance of acquired characters. All those assigned by Mr. Darwin,

together with others such, remain outstanding when we find that the

interpretation by _panmixia_ is untenable. Indeed, even had that hypothesis

been tenable, it would have been inapplicable to these cases; since in

domestic animals, artificially fed and often overfed, the supposed

advantage from economy cannot be shown to tell; and since, in these cases,

individuals are not naturally selected during the struggle for life, in

which certain traits are advantageous, but are artificially selected by man

without regard to such traits. Should it be urged that the assigned facts

are not numerous, it may be replied that there are no persons whose

occupations and amusements incidentally bring out such facts; and that they

are probably as numerous as those which would have been available for Mr.

Darwin's hypothesis, had there been no breeders and fanciers and gardeners

who, in pursuit of their profits and hobbies, furnished him with evidence.

It may be added that the required facts are not likely to be numerous, if

biologists refuse to seek for them.

See, then, how the case stands. Natural selection, or survival of the

fittest, is almost exclusively operative throughout the vegetal world and

throughout the lower animal world, characterized by relative passivity. But

with the ascent to higher types of animals, its effects are in increasing

degrees involved with those produced by inheritance of acquired characters;

until, in animals of complex structures, inheritance of acquired characters

becomes an important, if not the chief, cause of evolution. We have seen

that natural selection cannot work any changes in organisms save such as

conduce in considerable degrees, directly or indirectly, to the

multiplication of the stirp; whence failure to account for various changes

ascribed to it. And we have seen that it yields no explanation of the

co-adaptation of co-operative parts, even when the co-operation is

relatively simple, and still less when it is complex. On the other hand, we

see that if, along with the transmission of generic and specific

structures, there tend to be transmitted modifications arising in a certain

way, there is a strong _a priori_ probability that there tend to be

transmitted modifications arising in all ways. We have a number of facts

confirming this inference, and showing that acquired characters are

inherited--as large a number as can be expected, considering the difficulty

of observing them and the absence of search. And then to these facts may be

added the facts with which this essay set out, concerning the distribution

of tactual discriminativeness. While we saw that these are inexplicable by

survival of the fittest, we saw that they are clearly explicable as

resulting from the inheritance of acquired characters. And here let it be

added that this conclusion is conspicuously warranted by one of the methods

of inductive logic, known as the method of concomitant variations. For

throughout the whole series of gradations in perceptive power, we saw that

the amount of the effect is proportionate to the amount of the alleged

cause.

II.

Apart from those more special theories of Professor Weismann I lately dealt

with, the wide acceptance of which by the biological world greatly

surprises me, there are certain more general theories of his--fundamental

theories--the acceptance of which surprises me still more. Of the two on

which rests the vast superstructure of his speculations, the first concerns

the distinction between the reproductive elements of each organism and the

non-reproductive elements. He says:--

"Let us now consider how it happened that the multicellular animals and

plants, which arose from unicellular forms of life, came to lose this

power of living for ever.

"The answer to this question is closely bound up with the principle of

division of labour which appeared among multicellular organisms at a very

early stage....

"The first multicellular organism was probably a cluster of similar

cells, but these units soon lost their original homogeneity. As the

result of mere relative position, some of the cells were especially

fitted to provide for the nutrition of the colony, while others undertook

the work of reproduction." (_Essays upon Heredity_, i, p. 27)

Here, then, we have the great principle of the division of labour, which is

the principle of all organization, taken as primarily illustrated in the

division between the reproductive cells and the non-reproductive or somatic

cells--the cells devoted to the continuance of the species, and the cells

which subserve the life of the individual. And the early separation of

reproductive cells from somatic cells, is alleged on the ground that this

primary division of labour is that which arises between elements devoted to

species-life and elements devoted to individual life. Let us not be content

with words but look at the facts.

When Milne-Edwards first used the phrase "physiological division of

labour," he was obviously led to do so by perceiving the analogy between

the division of labour in a society, as described by political economists,

and the division of labour in an organism. Every one who reads has been

familiarized with the first as illustrated in the early stages, when men

were warriors while the cultivation and drudgery were done by slaves and

women; and as illustrated in the later stages, when not only are

agriculture and manufactures carried on by separate classes, but

agriculture is carried on by landlords, farmers, and labourers, while

manufactures, multitudinous in their kinds, severally involve the actions

of capitalists, overseers, workers, &c., and while the great function of

distribution is carried on by wholesale and retail dealers in different

commodities. Meanwhile students of biology, led by Milne-Edwards's phrase,

have come to recognize a parallel arrangement in a living creature; shown,

primarily, in the devoting of the outer parts to the general business of

obtaining food and escaping from enemies, while the inner parts are devoted

to the utilization of food, and supporting themselves and the outer parts;

and shown, secondarily, by the subdivision of these great functions into

those of various limbs and senses in the one case, and in the other case

into those of organs for digestion, respiration, circulation, excretion,

&c. But now let us ask what is the essential nature of this division of

labour. In both cases it is an _exchange of services_--an arrangement under

which, while one part devotes itself to one kind of action and yields

benefits to all the rest, all the rest, jointly and severally performing

their special actions, yield benefits to it in exchange. Otherwise

described, it is a system of _mutual_ dependence: A depends for its welfare

upon B, C, and D; B upon A, C, and D; and so with the rest: all depend upon

each and each upon all. Now let us apply this true conception of the

division of labour, to that which Professor Weismann calls a division of

labour. Where is the _exchange of services_ between somatic cells and

reproductive cells? There is none. The somatic cells render great services

to the reproductive cells, by furnishing them with materials for growth and

multiplication; but the reproductive cells render no services at all to the

somatic cells. If we look for the _mutual_ dependence we look in vain. We

find entire dependence on the one side and none on the other. Between the

parts devoted to individual life and the part devoted to species-life,

there is no division of labour whatever. The individual works for the

species; but the species works not for the individual. Whether at the stage

when the species is represented by reproductive cells, or at the stage when

it is represented by eggs, or at the stage when it is represented by young,

the parent does everything for it, and it does nothing for the parent. The

essential part of the conception is gone: there is no giving and receiving,

no exchange, no mutuality.

But now suppose we pass over this fallacious interpretation, and grant

Professor Weismann his fundamental assumption and his fundamental

corollary. Suppose we grant that because the primary division of labour is

that between somatic cells and reproductive cells, these two groups are the

first to be differentiated. Having granted this corollary, let us compare

it with the facts. As the alleged primary division of labour is universal,

so the alleged primary differentiation should be universal too. Let us see

whether it is so. Already, in the paragraph from which I have quoted above,

a crack in the doctrine is admitted: it is said that "this differentiation

was not at first absolute, and indeed it is not always so to-day." And

then, on turning to page 74, we find that the crack has become a chasm. Of

the reproductive cells it is stated that--"In Vertebrata they do not become

distinct from the other cells of the body until the embryo is completely

formed." That is to say, in this large and most important division of the

animal kingdom, the implied universal law does not hold. Much more than

this is confessed. Lower down the page we read--"There may be in fact cases

in which such separation does not take place until after the animal is

completely formed, and others, as I believe that I have shown, in which it

first arises one or more generations later, viz., in the buds produced by

the parent."

So that in other great divisions of the animal kingdom the alleged law is

broken; as among the _Coelenterata_ by the _Hydrozoa_, as among the

_Mollusca_ by the Ascidians, and as among the _Platyhelminthes_ by the

Trematode worms.

Following this admission concerning the _Vertebrata_, come certain

sentences which I partially italicize:--

"Thus, as their development shows, a marked antithesis exists between the

substance of the undying reproductive cells and that of the perishable

body-cells. We cannot explain this fact except _by the supposition_ that

each reproductive cell potentially contains two kinds of substance, which

at a variable time after the commencement of embryonic development,

separate from one another, and finally produce two sharply contrasted

groups of cells." (p. 74)

And a little lower down the page we meet with the lines:--

"_It is therefore quite conceivable_ that the reproductive cells might

separate from the somatic cells much later than in the examples mentioned

above, without changing the hereditary tendencies of which they are the

bearers."

That is to say, it is "quite conceivable" that after sexless _Cercariæ_

have gone on multiplying by internal gemmation for generations, the "two

kinds of substance" have, notwithstanding innumerable cell-divisions,

preserved their respective natures, and finally separate in such ways as to

produce reproductive cells. Here Professor Weismann does not, as in a case

before noted, assume something which it is "easy to imagine," but he

assumes something which it is difficult to imagine; and apparently thinks

that a scientific conclusion may be thereon safely based.

* * * * *

Associated with the assertion that the primary division of labour is

between the somatic cells and the reproductive cells, and associated with

the corollary that the primary differentiation is that which arises between

them, there goes another corollary. It is alleged that there exists a

fundamental distinction of nature between these two classes of cells. They

are described as respectively mortal and immortal, in the sense that those

of the one class are limited in their powers of multiplication, while those

of the other class are unlimited. And it is contended that this is due to

inherent unlikeness of nature.

Before inquiring into the truth of this proposition, I may fitly remark

upon a preliminary proposition set down by Professor Weismann. Referring to

the hypothesis that death depends "upon causes which lie in the nature of

life itself," he says:--

"I do not however believe in the validity of this explanation: I consider

that death is not a primary necessity, but that it has been secondarily

acquired as an adaptation. I believe that life is endowed with a fixed

duration, not because it is contrary to its nature to be unlimited, but

because the unlimited existence of individuals would be a luxury without

any corresponding advantage." (p. 24)

This last sentence has a teleological sound which would be appropriate did

it come from a theologian, but which seems strange as coming from a man of

science. Assuming, however, that the implication was not intended, I go on

to remark that Professor Weismann has apparently overlooked a universal law

of evolution--not organic only, but inorganic and super-organic--which

implies the necessity of death. The changes of every aggregate, no matter

of what kind, inevitably end in a state of equilibrium. Suns and planets

die, as well as organisms. The process of integration, which constitutes

the fundamental trait of all evolution, continues until it has brought

about a state which negatives further alterations, molar or molecular--a

state of balance among the forces of the aggregate and the forces which

oppose them.[108] In so far, therefore, as Professor Weismann's conclusions

imply the non-necessity of death, they cannot be sustained.

But now let us consider the above-described antithesis between the immortal

_Protozoa_ and the mortal _Metazoa_. An essential part of the theory is

that the _Protozoa_ can go on dividing and subdividing without limit, so

long as the fit external conditions are maintained. But what is the

evidence for this? Even by Professor Weismann's own admission there is no

proof. On p. 285 he says:--

"I could only consent to adopt the hypothesis of rejuvenescence [achieved

by conjugation], if it were rendered absolutely certain that reproduction

by division could never under any circumstances persist indefinitely. But

this cannot be proved with any greater certainty than the converse

proposition, and hence, as far as direct proof is concerned, the facts

are equally uncertain on both sides."

But this is an admission which seems to be entirely ignored when there is

alleged the contrast between the immortal _Protozoa_ and the mortal

_Metazoa_. Following Professor Weismann's method, it would be "easy to

imagine" that occasional conjugation is in all cases essential; and this

easily imagined conclusion might fitly be used to bar out his own. Indeed,

considering how commonly conjugation is observed, it may be held difficult

to imagine that it can in any cases be dispensed with. Apart from

imaginations of either kind, however, here is an acknowledgment that the

immortality of _Protozoa_ is not proved; that the allegation has no better

basis than the failure to observe cessation of fission; and that thus one

term of the above antithesis is not a fact, but is only an assumption.

And now what about the other term of the antithesis--the alleged inherent

mortality of the somatic cells? This we shall, I think, find is no more

defensible than the other. Such plausibility as it possesses disappears

when, instead of contemplating the vast assemblage of familiar cases which

animals present, we contemplate certain less familiar and unfamiliar cases.

By these we are shown that the usual ending of multiplication among somatic

cells is due, not to an intrinsic cause, but to extrinsic causes. Let us,

however, first look at Professor Weismann's own statements:--

"I have endeavoured to explain death as the result of restriction in the

powers of reproduction possessed by the somatic cells, and I have

suggested that such restriction may conceivably follow from a limitation

in the number of cell-generations possible for the cells of each organ

and tissue." (p. 28)

"The above-mentioned considerations show us that the degree of

reproductive activity present in the tissues is regulated by internal

causes while the natural death of an organism is the termination--the

hereditary limitation--of the process of cell-division, which began in

the segmentation of the ovum." (p. 30)

Now, though, in the above extracts there is mention of "internal causes"

determining "the degree of reproductive activity" of tissue cells, and

though, on page 28, the "causes of the loss" of the power of unlimited

cell-production "must be sought outside the organism, that is to say, in

the external conditions of life," yet the doctrine is that somatic cells

have become constitutionally unfitted for continued cell-multiplication.

"The somatic cells have lost this power to a gradually increasing extent,

so that at length they became restricted to a fixed, though perhaps very

large, number of cell-generations." (p. 28)

Examination will soon disclose good reasons for denying this inherent

restriction. We will look at the various causes which affect their

multiplication, and usually put a stop to increase after a certain point is

reached.

There is first the amount of vital capital given by the parent; partly in

the shape of a more or less developed structure, and partly in the shape of

bequeathed nutriment. Where this vital capital is small, and the young

creature, forthwith obliged to carry on physiological business for itself,

has to expend effort in obtaining materials for daily consumption as well

as for growth, a rigid restraint is put on that cell-multiplication

required for a large size. Clearly, the young elephant, starting with a big

and well-organized body, and supplied _gratis_ with milk during early

stages of growth, can begin physiological business on his own account on a

great scale; and by its large transactions his system is enabled to supply

nutriment to its multiplying somatic cells until they have formed a vast

aggregate--an aggregate such as it is impossible for a young mouse to

reach, obliged as it is to begin physiological business in a small way.

Then there is the character of the food in respect of its digestibility and

its nutritiveness. Here, that which the creature takes in requires much

grinding-up, or, when duly prepared, contains but a small amount of

available matter in comparison with the matter that has to be thrown away;

while there, the prey seized is almost pure nutriment, and requires but

little trituration. Hence, in some cases, an unprofitable physiological

business, and in other cases a profitable one; resulting in small or large

supplies to the multiplying somatic cells. Further, there has to be noted

the grade of visceral development, which, if low, yields only crude

nutriment slowly distributed, but which, if high, serves by its good

appliances for solution, depuration, absorption, and circulation, to yield

to the multiplying somatic cells a rich and pure blood. Then we come to an

all-important factor, the cost of obtaining food. Here large expenditure of

energy in locomotion is necessitated, and there but little--here great

efforts for small portions of food, and there small efforts for great

portions: again resulting in physiological poverty or physiological wealth.

Next, beyond the cost of nervo-muscular activities in foraging, there is

the cost of maintaining bodily heat. So much heat implies so much consumed

nutriment, and the loss by radiation or conduction, which has perpetually

to be made good, varies according to many circumstances--climate, medium

(as air or water), covering, size of body (small cooling relatively faster

than large); and in proportion to the cost of maintaining heat is the

abstraction from the supplies for cell-formation. Finally, there are three

all-important co-operative factors, or rather laws of factors, the effects

of which vary with the size of the animal. The first is that, while the

mass of the body varies as the cubes of its dimensions (_proportions_ being

supposed constant), the absorbing surface varies as the squares of its

dimensions; whence it results that, other things equal, increase of size

implies relative decrease of nutrition, and therefore increased obstacles

to cell-multiplication.[109] The second is a further sequence from these

laws--namely, that while the weight of the body increases as the cubes of

the dimensions, the sectional areas of its muscles and bones increase as

their squares; whence follows a decreasing power of resisting strains, and

a relative weakness of structure. This is implied in the ability of a small

animal to leap many times its own length, while a great animal, like the

elephant, cannot leap at all: its bones and muscles being unable to bear

the stress which would be required to propel its body through the air. What

increasing cost of keeping together the bodily fabric is thus entailed, we

cannot say; but that there is an increasing cost, which diminishes the

available, materials for increase of size, is beyond question.[110] And

then, in the third place, we have augmented expense of distribution of

nutriment. The greater the size becomes, the more force must be exerted to

send blood to the periphery; and this once more entails deduction from the

cell-forming matters.

Here, then, we have nine factors, several of them involving subdivisions,

which co-operate in aiding or restraining cell-multiplication. They occur

in endlessly varied proportions and combinations; so that every species

differs more or less from every other in respect of their effects. But in

all of them the co-operation is such as eventually arrests that

multiplication of cells which causes further growth; continues thereafter

to entail slow decrease in cell-multiplication, accompanying decline of

vital activities; and eventually brings cell-multiplication to an end. Now

a recognized principle of reasoning--the Law of Parsimony--forbids the

assumption of more causes than are needful for explanation of phenomena;

and since, in all such living aggregates as those above supposed, the

causes named inevitably bring about arrest of cell-multiplication, it is

illegitimate to ascribe this arrest to some inherent property in the cells.

Inadequacy of the other causes must be shown before an inherent property

can be rightly assumed.

For this conclusion we find ample justification when we contemplate types

of animals which lead lives that do not put such decided restraints on

cell-multiplication. First let us take an instance of the extent to which

(irrespective of natures of cells as reproductive or somatic)

cell-multiplication may go, where the conditions render nutrition easy and

reduce expenditure to a minimum. I refer to the case of the _Aphides_.

Though it is early in the season (March), the hothouses at Kew have

furnished a sufficient number of these to show that twelve of them weigh a

grain--a larger number than would be required were they full-sized. Citing

Professor Owen, who adopts the calculations of Tougard to the effect that

by agamic multiplication "a single impregnated ovum of _Aphis_ may give

rise, without fecundation, to a quintillion of _Aphides_," Professor Huxley

says:--

"I will assume that an Aphis weighs 1/1000 of a grain, which is certainly

vastly under the mark. A quintillion of _Aphides_ will, on this estimate,

weigh a quatrillion of grains. He is a very stout man who weighs two

million grains; consequently the tenth brood alone, if all its members

survive the perils to which they are exposed, contains more substance

than 500,000,000 stout men--to say the least, more than the whole

population of China!"[111]

And had Professor Huxley taken the actual weight, one-twelfth of a grain,

the quintillion of _Aphides_ would evidently far outweigh the whole human

population of the globe: five billions of tons being the weight, as brought

out by my own calculation! Of course I do not cite this in proof of the

extent to which multiplication of somatic cells, descending from a single

ovum, may go; because it will be contended, with some reason, that each of

the sexless _Aphides_, viviparously produced, arose by fission of a cell

which had descended from the original reproductive cell. I cite it merely

to show that when the cell-products of a fertilized ovum are perpetually

divided and subdivided into small groups, distributed over an unlimited

nutritive area, so that they can get materials for growth at no cost, and

expend nothing appreciable in motion or maintenance of temperature,

cell-production may go on without limit. For the agamic multiplication of

_Aphides_ has been shown to continue for four years, and to all appearance

would be ceaseless were the temperature and supply of food continued

without break. But now let us pass to analogous illustrations of cause and

consequence, open to no criticism of the kind just indicated. They are

furnished by various kinds of _Entozoa_, of which take the _Trematoda_,

infesting molluscs and fishes. Of one of them we read:--"_Gyrodactylus_

multiplies agamically by the development of a young Trematode within the

body, as a sort of internal bud. A second generation appears within the

first, and even a third within the second, before the young _Gyrodactylus_

is born."[112] And the drawings of Steenstrup, in his _Alternation of

Generations_, show us, among creatures of this group, a sexless individual

the whole interior of which is transformed into smaller sexless

individuals, which severally, before or after their emergence, undergo

similar transformations--a multiplication of somatic cells without any sign

of reproductive cells. Under what circumstances do such modes of agamic

multiplication, variously modified among parasites, occur? They occur where

there is no expenditure whatever in motion or maintenance of temperature,

and where nutriment surrounds the body on all sides. Other instances are

furnished by groups in which, though the nutriment is not abundant, the

cost of living is almost unappreciable. Among the _Coelenterata_ there are

the Hydroid Polyps, simple and compound; and among the _Mollusca_ we have

various types of Ascidians, fixed and floating, _Botryllidæ_ and _Salpæ_.

But now from these low animals in which sexless reproduction, and continued

multiplication of somatic cells, is common, and one class of which is named

"zoophytes," because its form of life simulates that of plants, let us pass

to plants themselves. In these there is no expenditure in effort, there is

no expenditure in maintaining temperature, and the food, some of it

supplied by the earth, is the rest of it supplied by a medium which

everywhere bathes the outer surface: the utilization of its contained

material being effected _gratis_ by the Sun's rays. Just as was to be

expected, we here find that agamogenesis may go on without end. Numerous

plants and trees are propagated to an unlimited extent by cuttings and

buds; and we have sundry plants which cannot be otherwise propagated. The

most familiar are the double roses of our gardens: these do not seed, and

yet have been distributed everywhere by grafts and buds. Hothouses furnish

many cases, as I learn from an authority second to none. Of "the whole host

of tropical orchids, for instance, not one per cent. has ever seeded, and

some have been a century under cultivation." Again, we have the _Acorus

calamus_, "that has hardly been known to seed anywhere, though it is found

wild all over the north temperate hemisphere." And then there is the

conspicuous and conclusive case of _Eloidea Canadensis_ (alias

_Anacharis_,) introduced no one knows how (probably with timber), and first

observed in 1847, in several places; and which, having since spread over

nearly all England, now everywhere infests ponds, canals, and slow rivers.

The plant is dioecious, and only the female exists here. Beyond all

question, therefore, this vast progeny of the first slip or fragment

introduced, sufficient to cover many square miles were it put together, is

constituted entirely of somatic cells. Hence, as far as we can judge, these

somatic cells are immortal in the sense given to the word by Professor

Weismann; and the evidence that they are so is immeasurably stronger than

the evidence which leads him to assert immortality for the

fissiparously-multiplying _Protozoa_. This endless multiplication of

somatic cells has been going on under the eyes of numerous observers for

forty odd years. What observer has watched for forty years to see whether

the fissiparous multiplication of _Protozoa_ does not cease? What observer

has watched for one year, or one month, or one week?[113]

Even were not Professor Weismann's theory disposed of by this evidence, it

might be disposed of by a critical examination of his own evidence, using

his own tests. Clearly, if we are to measure relative mortalities, we must

assume the conditions to be the same and must use the same measure. Let us

do this with some appropriate animal--say Man, as the most open to

observation. The mortality of the somatic cells constituting the mass of

the human body, is, according to Professor Weismann, shown by the decline

and final cessation of cell-multiplication in its various organs. Suppose

we apply this test to all the organs: not to those only in which there

continually arise bile-cells, epithelium-cells, &c., but to those also in

which there arise reproductive cells. What do we find? That the

multiplication of these last comes to an end long before the multiplication

of the first. In a healthy woman, the cells which constitute the various

active tissues of the body, continue to grow and multiply for many years

after germ-cells have died out. If similarly measured, then, these cells of

the last class prove to be more mortal than those of the first. But

Professor Weismann uses a different measure for the two classes of cells.

Passing over the illegitimacy of this proceeding, let us accept his other

mode of measurement, and see what comes of it. As described by him, absence

of death among the _Protozoa_ is implied by that unceasing division and

subdivision of which they are said to be capable. Fission continued without

end, is the definition of the immortality he speaks of. Apply this

conception to the reproductive cells in a _Metazoon_. That the immense

majority of them do not multiply without end, we have already seen: with

very rare exceptions they die and disappear without result, and they cease

their multiplication while the body as a whole still lives. But what of

those extremely exceptional ones which, as being actually instrumental to

the maintenance of the species, are alone contemplated by Professor

Weismann? Do these continue their fissiparous multiplications without end?

By no means. The condition under which alone they preserve a qualified form

of existence, is that, instead of one becoming two, two become one. A

member of series A and a member of series B, coalesce; and so lose their

individualities. Now, obviously, if the immortality of a series is shown if

its members divide and subdivide perpetually, then the opposite of

immortality is shown when, instead of division, there is union. Each series

ends, and there is initiated a new series, differing more or less from

both. Thus the assertion that the reproductive cells are immortal, can be

defended only by changing the conception of immortality otherwise implied.

Even apart from these last criticisms, however, we have clear disproof of

the alleged inherent difference between the two classes of cells. Among

animals, the multiplication of somatic cells is brought to an end by sundry

restraining conditions; but in various plants, where these restraining

conditions are absent, the multiplication is unlimited. It may, indeed, be

said that the alleged distinction should be reversed; since the fissiparous

multiplication of reproductive cells is necessarily interrupted from time

to time by coalescence, while that of the somatic cells may go on for a

century without being interrupted.

* * * * *

In the essay to which this is a postscript, conclusions were drawn from the

remarkable case of the horse and the quagga, there narrated, along with an

analogous case observed among pigs. These conclusions have since been

confirmed. I am much indebted to a distinguished correspondent who has

drawn my attention to verifying facts furnished by the offspring of whites

and negroes in the United States. Referring to information given him many

years ago, he says:--"It was to the effect that the children of white women

by a white father, had been _repeatedly_ observed to show traces of black

blood, in cases when the woman had previous connection with [_i. e._ a

child by] a negro." At the time I received this information, an American

was visiting me; and, on being appealed to, answered that in the United

States there was an established belief to this effect. Not wishing,

however, to depend upon hearsay, I at once wrote to America to make

inquiries. Professor Cope of Philadelphia has written to friends in the

South, but has not yet sent me the results. Professor Marsh, the

distinguished palæontologist, of Yale, New Haven, who is also collecting

evidence, sends a preliminary letter in which he says:--"I do not myself

know of such a case, but have heard many statements that make their

existence probable. One instance, in Connecticut, is vouched for so

strongly by an acquaintance of mine, that I have good reason to believe it

to be authentic."

That cases of the kind should not be frequently seen in the North,

especially nowadays, is of course to be expected. The first of the above

quotations refers to facts observed in the South during slavery days; and

even then, the implied conditions were naturally very infrequent. Dr. W. J.

Youmans of New York has, on my behalf, interviewed several medical

professors, who, though they have not themselves met with instances, say

that the alleged result, described above, "is generally accepted as a

fact." But he gives me what I think must be regarded as authoritative

testimony. It is a quotation from the standard work of Professor Austin

Flint, and runs as follows:--

"A peculiar and, it seems to me, an inexplicable fact is, that previous

pregnancies have an influence upon offspring. This is well known to

breeders of animals. If pure-blooded mares or bitches have been once

covered by an inferior male, in subsequent fecundations the young are

likely to partake of the character of the first male, even if they be

afterwards bred with males of unimpeachable pedigree. What the mechanism

of the influence of the first conception is, it is impossible to say; but

the fact is incontestable. The same influence is observed in the human

subject. A woman may have, by a second husband, children who resemble a

former husband, and this is particularly well marked in certain instances

by the colour of the hair and eyes. A white woman who has had children by

a negro may subsequently bear children to a white man, these children

presenting some of the unmistakable peculiarities of the negro

race."[114]

Dr. Youmans called on Professor Flint, who remembered "investigating the

subject at the time his larger work was written [the above is from an

abridgment], and said that he had never heard the statement questioned."

Some days before I received this letter and its contained quotation, the

remembrance of a remark I heard many years ago concerning dogs, led to the

inquiry whether they furnished analogous evidence. It occurred to me that a

friend who is frequently appointed judge of animals at agricultural shows,

Mr. Fookes, of Fairfield, Pewsey, Wiltshire, might know something about the

matter. A letter to him brought various confirmatory statements. From one

"who had bred dogs for many years" he learnt that--

"It is a well known and admitted fact that if a bitch has two litters by

two different dogs, the character of the first father is sure to be

perpetuated in any litters she may afterwards have, no matter how

pure-bred a dog may be the begetter."

After citing this testimony, Mr. Fookes goes on to give illustrations known

to himself.

"A friend of mine near this had a very valuable Dachshund bitch, which

most unfortunately had a litter by a stray sheep-dog. The next year her

owner sent her on a visit to a pure Dachshund dog, but the produce took

quite as much of the first father as the second, and the next year he

sent her to another Dachshund with the same result. Another case:--A

friend of mine in Devizes had a litter of puppies, unsought for, by a

setter from a favourite pointer bitch, and after this she never bred any

true pointers, no matter of what the paternity was."

[Since the publication of this article additional evidences have come to

hand. One is from the late Prof. Riley, State Entomologist at Washington,

who says that telegony is an "established principle among well-educated

farmers" in the United States, and who gives me a case in horse-breeding

to which he was himself witness.

Mr. W. P. Smith, writing from Stoughton Grange, Guildford, but giving the

results of his experiences in America, says that "the fact of a previous

conception influencing subsequent offspring was so far recognised among

American cattle-breeders" that it was proposed to raise the rank of any

heifer that had borne a first calf by a thoroughbred bull, and though

this resolution when brought before one of the chief societies was not

carried, yet on all sides it was admitted that previous conceptions had

effects of the kind alleged. Mr. Smith in another letter says:--"When I

had a large mule and horse ranche in America I noticed that the foals of

mares by horse stallions had a mulish appearance in those cases where the

mare had previously given birth to a mule foal. Common heifers who have

had calves by a thoroughbred bull are apt thereafter to have well-bred

calves even from the veriest scrubs."

Yet another very interesting piece of evidence is furnished by Mr. W.

Sedgwick, M.R.C.S., in an article on "The Influence of Heredity in

Disease," published in the _British Medical Journal_ for Feb. 22, 1896,

pp. 460-2. It concerns the transmission of a malformation known among

medical men as hypospadias. Referring to a man belonging to a family in

which this defect prevailed, he writes:--"The widow of the man from whom

these three generations of hypospadians were descended married again,

after an interval of eighteen months; and in this instance the second

husband was not only free from the defect, but there was no history of it

in his family. By this second marriage she had four hypospadiac sons and

four hypospadiac grandsons; whilst there were seven grandsons and three

great-grandsons who were not malformed."]

Coming from remote places, from those who have no theory to support, and

who are some of them astonished by the unexpected phenomena, the agreement

dissipates all doubt. In four kinds of mammals, widely divergent in their

natures--man, horse, dog, and pig--we have this same seemingly-anomalous

kind of heredity, made visible under analogous conditions. We must take it

as a demonstrated fact that, during gestation, traits of constitution

inherited from the father produce effects upon the constitution of the

mother; and that these communicated effects are transmitted by her to

subsequent offspring. We are supplied with an absolute disproof of

Professor Weismann's doctrine that the reproductive cells are independent

of, and uninfluenced by, the somatic cells; and there disappears absolutely

the alleged obstacle to the transmission of acquired characters.

* * * * *

Notwithstanding experiences showing the futility of controversy for the

establishment of truth, I am tempted here to answer opponents at some

length. But even could the editor allow me the needful space, I should be

compelled, both by lack of time and by ill-health, to be brief. I must

content myself with noticing a few points which most nearly concern me.

Referring to my argument respecting tactual discriminativeness, Mr. Wallace

thinks that I--

"afford a glaring example of taking the unessential in place of the

essential, and drawing conclusions from a partial and altogether

insufficient survey of the phenomena. For this 'tactual

discriminativeness,' which is alone dealt with by Mr. Spencer, forms the

least important, and probably only an incidental portion of the great

vital phenomenon of skin-sensitiveness, which is at once the watchman and

the shield of the organism against imminent external dangers."

(_Fortnightly Review_, April, 1893, p. 497)

Here Mr. Wallace assumes it to be self-evident that skin-sensitiveness is

due to natural selection, and assumes that this must be admitted by me. He

supposes it is only the unequal distribution of skin-discriminativeness

which I contend is not thus accounted for. But I deny that either the

general sensitiveness or the special sensitiveness results from natural

selection; and I have years ago justified the first disbelief as I have

recently the second. In "The Factors of Organic Evolution" (_Essays_,

454-8), I have given various reasons for inferring that the genesis of the

nervous system cannot be due to survival of the fittest; but that it is due

to the direct effects of converse between the surface and the environment;

and that thus only is to be explained the strange fact that the nervous

centres are originally superficial, and migrate inwards during development.

These conclusions I have, in the essay Mr. Wallace criticizes, upheld by

the evidence which blind boys and skilled compositors furnish; proving, as

this does, that increased nervous development is peripherally initiated.

Mr. Wallace's belief that skin-sensitiveness arose by natural selection, is

unsupported by a single fact. He assumes that it _must_ have been so

produced because it is all-important to self-preservation. My belief that

it is directly initiated by converse with the environment, is supported by

facts; and I have given proof that the assigned cause is now in operation.

Am I called upon to abandon my own supported belief and accept Mr.

Wallace's unsupported belief? I think not.

Referring to my argument concerning blind cave-animals, Professor

Lankester, in _Nature_ of February 23, 1893, writes:--

"Mr. Spencer shows that the saving of ponderable material in the

suppression of an eye is but a small economy: he loses sight of the fact,

however, that possibly, or even probably, the saving to the organism in

the reduction of an eye to a rudimentary state is not to be measured by

mere bulk, but by the non-expenditure of special materials and special

activities which are concerned in the production of an organ so peculiar

and elaborate as is the vertebrate eye."

It seems to me that a supposition is here made to do duty as a fact; and

that I might with equal propriety say that "possibly, or even probably,"

the vertebrate eye is physiologically cheap: its optical part, constituting

nearly its whole bulk, consisting of a low order of tissue. There is,

indeed, strong reason for considering it physiologically cheap. If any one

remembers how relatively enormous are the eyes of a fish just out of the

egg--a pair of eyes with a body and head attached; and if he then remembers

that every egg contains material for such a pair of eyes; he will see that

eye-material constitutes a very considerable part of the fish's roe; and

that, since the female fish provides this quantity every year, it cannot be

expensive. My argument against Weismann is strengthened rather than

weakened by contemplation of these facts.

Professor Lankester asks my attention to a hypothesis of his own, published

in the _Encyclopædia Britannica_, concerning the production of blind

cave-animals. He thinks it can--

"be fully explained by natural selection acting on congenital fortuitous

variations. Many animals are thus born with distorted or defective eyes

whose parents have not had their eyes submitted to any peculiar

conditions. Supposing a number of some species of Arthropod or Fish to be

swept into a cavern or to be carried from less to greater depths in the

sea, those individuals with perfect eyes would follow the glimmer of

light and eventually escape to the outer air or the shallower depths,

leaving behind those with imperfect eyes to breed in the dark place. A

natural selection would thus be effected" in successive generations.

First of all, I demur to the words "many animals." Under the abnormal

conditions of domestication, congenitally defective eyes may be not very

uncommon; but their occurrence under natural conditions is, I fancy,

extremely rare. Supposing, however, that in a shoal of young fish, there

occur some with eyes seriously defective. What will happen? Vision is

all-important to the young fish, both for obtaining food and for escaping

from enemies. This is implied by the immense development of eyes just

referred to; and the obvious conclusion to be drawn is that the partially

blind would disappear. Considering that out of the enormous number of young

fish hatched with perfect eyes, not one in a hundred reaches maturity, what

chance of surviving would there be for those with imperfect eyes?

Inevitably they would be starved or be snapped up. Hence the chances that a

matured or partially matured semi-blind fish, or rather two such, male and

female, would be swept into a cave and left behind are extremely remote.

Still more remote must the chances be in the case of cray-fish. Sheltering

themselves as these do under stones, in crevices, and in burrows which they

make in the banks, and able quickly to anchor themselves to weeds or sticks

by their claws, it seems scarcely supposable that any of them could be

carried into a cave by a flood. What, then, is the probability that there

will be two nearly blind ones, and that these will be thus carried? Then,

after this first extreme improbability, there comes a second, which we may,

I think, rather call an impossibility. How would it be possible for

creatures subject to so violent a change of habitat to survive? Surely

death would quickly follow the subjection to such utterly unlike conditions

and modes of life. The existence of these blind cave-animals can be

accounted for only by supposing that their remote ancestors began making

excursions into the cave, and, finding it profitable, extended them,

generation after generation, further in: undergoing the required

adaptations little by little.[115]

Between Dr. Romanes and myself the first difference concerns the

interpretation of "Panmixia." Clearer conceptions of these matters would be

reached if, instead of thinking in abstract terms, the physiological

processes concerned were brought into the foreground. Beyond the production

of changes in the sizes of parts by the selection of fortuitously-arising

variations, I can see but one other cause for the production of them--the

competition among the parts for nutriment. This has the effect that active

parts are well-supplied and grow, while inactive parts are ill-supplied and

dwindle.[116] This competition is the cause of "economy of growth"; this is

the cause of decrease from disuse; and this is the only conceivable cause

of that decrease which Dr. Romanes contends follows the cessation of

selection. The three things are aspects of the same thing. And now, before

leaving this question, let me remark on the strange proposition which has

to be defended by those who deny the dwindling of organs from disuse. Their

proposition amounts to this:--that for a hundred generations an inactive

organ may be partially denuded of blood all through life, and yet in the

hundredth generation will be produced of just the same size as in the

first!