PHILOSOPHY OF DR. ERASMUS DARWIN.
Considering the wide reputation enjoyed by Dr. Darwin at the beginning
of this century, it is surprising how completely he has been lost sight
of. The 'Botanic Garden' was translated into Portuguese in 1803; the
'Loves of the Plants' into French and Italian in 1800 and 1805; while,
as I have already said, the 'Zoonomia' had appeared some years earlier
in Germany. Paley's 'Natural Theology' is written throughout at the
'Zoonomia,' though he is careful, _more suo_, never to mention this work
by name. Paley's success was probably one of the chief causes of the
neglect into which the Buffonian and Darwinian systems fell in this
country. Dr. Darwin is as reticent about teleology as Buffon, and
presumably for the same reason, but the evidence in favour of design was
too obvious; Paley, therefore, with his usual keen-sightedness seized
upon this weak point, and had the battle all his own way, for Dr. Darwin
died the same year as that in which the 'Natural Theology' appeared. The
unfortunate failure to see that evolution involves design and purpose as
necessarily and far more intelligibly than the theological view of
creation, has retarded our perception of many important facts for
three-quarters of a century.
However this may be, Dr. Darwin's name has been but little before the
public during the controversies of the last thirty years. Mr. Charles
Darwin, indeed, in the "historical sketch" which he has prefixed to the
later editions of his 'Origin of Species,' says, "It is curious how
largely my grandfather, Dr. Erasmus Darwin, anticipated the views and
erroneous grounds of opinion of Lamarck in his 'Zoonomia,' vol. i. pp.
500-510, published in 1794."[155] And a few lines lower Mr. Darwin adds,
"It is rather a singular instance of the manner in which similar views
arise at about the same time, that Goethe in Germany, and Geoffroy St.
Hilaire (as we shall immediately see) in France, came to the same
conclusion on the 'Origin of Species' in the years 1794-1796."
Acquaintance with Buffon's work will explain much of the singularity,
while those who have any knowledge of the writings of Dr. Darwin and
Etienne Geoffroy St. Hilaire will be aware that neither would admit the
other as "coming to the same conclusion," or even nearly so, as himself.
Dr. Darwin goes beyond his successor, Lamarck, while Etienne Geoffroy
does not even go so far as Dr. Darwin's predecessor, Buffon, had thought
fit to let himself be known as going. I have found no other reference to
Dr. Darwin in the 'Origin of Species,' except the two just given from
the same note. In the first edition I find no mention of him.
The chief fault to be found with Dr. Darwin's treatise on evolution is
that there is not enough of it; what there is, so far from being
"erroneous," is admirable. But so great a subject should have had a book
to itself, and not a mere fraction of a book. If his opponents, not
venturing to dispute with him, passed over one book in silence, he
should have followed it up with another, and another, and another, year
by year, as Buffon and Lamarck did; it is only thus that men can expect
to succeed against vested interests. Dr. Darwin could speak with a
freedom that was denied to Buffon. He took Buffon at his word as well as
he could, and carried out his principles to what he conceived to be
their logical conclusion. This was doubtless what Buffon had desired and
reckoned on, but, as I have said already, I question how far Dr. Darwin
understood Buffon's humour; he does not present any of the phenomena of
having done so, and therefore I am afraid he must be said to have missed
it.
Like Buffon, Dr. Darwin had no wish to see far beyond the obvious; he
missed good things sometimes, but he gained more than he lost; he knew
that it is always on the margin, as it were, of the self-evident that
the greatest purchase against the nearest difficulty is obtainable. His
life was not one of Herculean effort, but, like the lives of all those
organisms that are most likely to develop and transmit a useful
modification, it was one of well-sustained activity; it was a
long-continued keeping open of the windows of his own mind, much after
the advice he gave to the Nottingham weavers. Dr. Darwin knew, and, I
imagine, quite instinctively, that nothing tends to oversight like
overseeing. He does not trouble himself about the origin of life; as
for the perceptions and reasoning faculties of animals and plants, it is
enough for him that animals and plants do things which we say involve
sensation and consciousness when we do them ourselves or see others do
them. If, then, plants and animals appear as if they felt and
understood, let the matter rest there, and let us say they feel and
understand--being guided by the common use of language, rather than by
any theories concerning brain and nervous system. If any young writer
happens to be in want of a subject, I beg to suggest that he may find
his opportunity in a 'Philosophy of the Superficial.'
Though Dr. Darwin was more deeply impressed than Buffon with the oneness
of personality between parents and offspring, so that these latter are
not "new" creatures, but "elongations of the parents," and hence "may
retain some of the habits of the parent system," he did not go on to
infer definitely all that he might easily have inferred from such a
pregnant premiss. He did not refer the repetition by offspring, of
actions which their parents have done for many generations, but which
they can never have seen those parents do, to the memory (in the strict
sense of the word) of their having done those actions when they were in
the persons of their parents; which memory, though dormant until
awakened by the presence of associated ideas, becomes promptly kindled
into activity when a sufficient number of these ideas are reproduced.
This, I gather, is the theory put forward by Professor Hering, of whose
work, however, I know no more than is told us by Professor Ray
Lankester in an article which, appeared in 'Nature,' July 13th, 1876.
This theory seems to be adopted by Professor Haeckel, and to receive
support from Professor Ray Lankester himself. Knowing no German, I have
been unable to make myself acquainted with Professor Hering's position
in detail, but its similarity to, if not identity with, that taken by
myself subsequently, but independently, in 'Life and Habit,' seems
sufficiently established by the following extracts; it is to be wished,
however, that a full account of this lecture were accessible to English
readers. The extracts are as follows:--
"Professor Hering has the merit of introducing some striking phraseology
into his treatment of the subject which serves to emphasize the leading
idea. He points out that since all transmission of 'qualities' from cell
to cell in the growth and repair of one and the same organ, or from
parent to offspring, is a transmission of vibrations or affections of
material particles, whether these qualities manifest themselves as form,
or as a facility for entering on a given series of vibrations, we may
speak of all such phenomena as 'memory,' whether it be the conscious
memory exhibited by the nerve cells of the brain or the unconscious
memory we call habit, or the inherited memory we call instinct; or
whether, again, it be the reproduction of parental form and minute
structure. All equally may be called the 'memory of living matter.' From
the earliest existence of protoplasm to the present day the memory of
living matter is continuous. Though individuals die, the universal
memory of living matter is carried on.
"Professor Hering, in short, helps us to a comprehensive conception of
the nature of heredity and adaptation, by giving us the term 'memory'
conscious or unconscious, for the continuity of Mr. Herbert Spencer's
polar forces, or polarities of physiological units.
. . . . . .
"The undulatory movement of the plastidules is the key to the mechanical
explanation of all the essential phenomena of life. The plastidules are
liable to have their undulations affected by every external force, and,
once modified, the movement does not return to its pristine condition.
By assimilation they continually increase to a certain point in size,
and then divide, and thus perpetuate in the undulatory movement of
successive generations, the impressions or resultants due to the action
of external agencies on individual plastidules. This is Memory. All
plastidules possess memory; and Memory which we see in its ultimate
analysis is identical with reproduction, is the distinguishing feature
of the plastidule; is that which it alone of all molecules possesses, in
addition to the ordinary properties of the physicist's molecule; is, in
fact, that which distinguishes it as vital. To the sensitiveness of the
movement of plastidules is due Variability--to their unconscious Memory
the power of Hereditary Transmission. As we know them to-day they may
'have learnt little, and forgotten nothing' in one organism, and 'have
learnt much, and forgotten much' in another; but in all, their memory if
sometimes fragmentary, yet reaches back to the dawn of life upon the
earth.--E. Ray Lankester."
Nothing can well be plainer and more uncompromising than the above.
Professor Hering would, I gather, no less than myself, refer the
building of its nest by a bird to the intense--but unconscious, owing to
its very perfection and intensity--recollection by the bird of the nests
it built when it was in the persons of its ancestors; this memory would
begin to stimulate action when the surrounding associations, such as
temperature, state of vegetation, &c., reminded it of the time when it
had been in the habit of beginning to build in countless past
generations. Dr. Darwin does not go so far as this. He says that wild
birds choose spring as their building time "from their _acquired_
knowledge that the mild temperature of the air is more convenient for
hatching their eggs," and a little lower down he speaks of the fact that
graminivorous animals generally produce their young in spring, as "part
of the traditional knowledge which they learn _from the example_ of
their parents."[156]
Again he says, that birds "seem to be instructed how to build their
nests _from their observation_ of that in which they were educated, and
from their knowledge of those things that are most agreeable to their
touch in respect to warmth, cleanliness, and stability."
Had Dr. Darwin laid firmly hold of two superficial facts concerning
memory which we can all of us test for ourselves--I mean its dormancy
until kindled by the return of a sufficient number of associated ideas,
and its unselfconsciousness upon becoming intense and perfect--and had
he connected these two facts with the unity of life through successive
generations--an idea which plainly haunted him--he would have been
saved from having to refer instinct to imitation, in the face of the
fact that in a thousand instances the creature imitating can never have
seen its model, save when it was a part of its parents,--seeing what
they saw, doing what they did, feeling as they felt, and remembering
what they remembered.
Miss Seward tells us that Dr. Darwin read his chapter on instinct "to a
lady who was in the habit of rearing canary birds. She observed that the
pair which he then saw building their nest in her cage, were a male and
female, who had been hatched and reared in that very _cage_, and were
not in existence when the mossy cradle was fabricated in which _they_
first saw light." She asked him, and quite reasonably, "how, upon his
principle of imitation, he could account for the nest he then saw
building, being constructed even to the precise disposal of every hair
and shred of wool upon the model of _that_ in which the pair were born,
and on which every other canary bird's nest is constructed, when the
proper materials are furnished. That of the pyefinch," she added, "is of
much compacter form, warmer, and more comfortable. Pull one of these
nests to pieces for its materials; and place another nest before these
canary birds as a pattern, and see if they will make the slightest
attempt to imitate their model! No, the result of their labour will,
upon instinctive hereditary impulse, be exactly the slovenly little
mansion of their race, the same with that which their parents built
before themselves were hatched. The Doctor could not do away the force
of that single fact, with which his system was incompatible, yet he
maintained that system with philosophic sturdiness, though experience
brought confutation from a thousand sources."[157]
As commonly happens in such disputes, both were right and both were
wrong. The lady was right in refusing to refer instinct to imitation,
and the Doctor was right in maintaining reason and instinct to be but
different degrees of perfection of the same mental processes. Had he
substituted "memory" for "imitation," and asked the lady to define
"sameness" or "personal identity," he would have soon secured his
victory.
The main fact, compared with which all else is a matter of detail, is
the admission that instinct is only reason become habitual. This
admission involves, consciously or unconsciously, the admission of all
the principles contended for in 'Life and Habit'; principles which, if
admitted, make the facts of heredity intelligible by showing that they
are of the same character as other facts which we call intelligible, but
denial of which makes nonsense of half the terms in common use
concerning it. For the view that instinct is habitual reason involves
sameness of personality and memory as common to parents and offspring;
it involves also the latency of that memory till rekindled by the return
of a sufficient number of its associated ideas, and points the
unconsciousness with which habitual actions are performed. These
principles being grasped, the infertility _inter se_ of widely distant
species, the commonly observed sterility of hybrids, the sterility of
certain animals and plants under confinement, the phenomena of old age
as well as those of growth, and the principle which underlies longevity
and alternate generations, follow logically and coherently, as I showed
in 'Life and Habit.' Moreover, we find that the terms in common use show
an unconscious sense that some such view as I have insisted on was
wanted and would come, for we find them made and to hand already; few if
any will require altering; all that is necessary is to take common words
according to their common meanings.
Dr. Darwin is very good on this head. Here, as everywhere throughout his
work, if things or qualities appear to resemble one another sufficiently
and without such traits of unlikeness, on closer inspection, as shall
destroy the likeness which was apparent at first, he connects them, all
theories notwithstanding. I have given two instances of his manner of
looking at instinct and reason.[158] "If these are not," he concludes,
"deductions _from their own previous experience, or observation_, all
the actions of mankind must be resolved into instincts."[159]
If by "previous experience" we could be sure that Dr. Darwin
persistently meant "previous experience in the persons of their
ancestors," he would be in an impregnable position. As it is, we feel
that though he had caught sight of the truth, and had even held it in
his hands, yet somehow or other it just managed to slip through his
fingers.
Again he writes:--
"So flies burn themselves in candles, deceived like mankind by the
misapplication of their knowledge."
Again:--
"An ingenious philosopher has lately denied that animals can enter into
contracts, and thinks this an essential difference between them and the
human creature: but does not daily observation convince us that they
form contracts of friendship with each other and with mankind? When
puppies and kittens play together is there not a tacit contract that
they will not hurt each other? And does not your favourite dog expect
you should give him his daily food for his services and attention to
you? And thus barters his love for your protection? In the same manner
that all contracts are made among men that do not understand each
other's arbitrary language."[160]
One more extract from a chapter full of excellent passages must suffice.
"One circumstance I shall relate which fell under my own eye, and showed
the power of reason in a wasp, as it is exercised among men. A wasp on a
gravel walk had caught a fly nearly as large as himself; kneeling on the
ground, I observed him separate the tail and the head from the body
part, to which the wings were attached. He then took the body part in
his paws, and rose about two feet from the ground with it; but a gentle
breeze wafting the wings of the fly turned him round in the air, and he
settled again with his prey upon the gravel. I then distinctly observed
him cut off with his mouth first one of the wings and then the other,
after which he flew away with it, unmolested by the wind.
"Go, proud reasoner, and call the worm thy sister!"[161]
Dr. Darwin's views on the essential unity of animal and vegetable life
are put forward in the following admirable chapter on "Vegetable
Animation," which I will give in full, and which is confirmed in all
important respects by the latest conclusions of our best modern
scientists, so, at least, I gather from Mr. Francis Darwin's interesting
lecture.[162]
"I. 1. The fibres of the vegetable world, as well as those of the
animal, are excitable into a variety of motion by irritations of
external objects. This appears particularly in the mimosa or sensitive
plant, whose leaves contract on the slightest injury: the _Dionaea
muscipula_, which was lately brought over from the marshes of America,
presents us with another curious instance of vegetable irritability; its
leaves are armed with spines on their upper edge, and are spread on the
ground around the stem; when an insect creeps on any of them in its
passage to the flower or seed, the leaf shuts up like a steel rat-trap,
and destroys its enemy.[163]
"The various secretions of vegetables as of odour, fruit, gum, resin,
wax, honey, seem brought about in the same manner as in the glands of
animals; the tasteless moisture of the earth is converted by the hop
plant into a bitter juice; as by the caterpillar in the nutshell, the
sweet powder is converted into a bitter powder. While the power of
absorption in the roots and barks of vegetables is excited into action
by the fluids applied to their mouths like the lacteals and lymphatics
of animals.
"2. The individuals of the vegetable world may be considered as inferior
or less perfect animals; a tree is a congeries of many living buds, and
in this respect resembles the branches of the coralline, which are a
congeries of a multitude of animals. Each of these buds of a tree has
its proper leaves or petals for lungs, produces its viviparous or its
oviparous offspring in buds or seeds; has its own roots, which,
extending down the stem of the tree, are interwoven with the roots of
the other buds, and form the bark, which is the only living part of the
stem, is annually renewed and is superinduced upon the former bark,
which then dies, and, with its stagnated juices gradually hardening into
wood, forms the concentric circles which we see in blocks of timber.
"The following circumstances evince the individuality of the buds of
trees. First, there are many trees whose whole internal wood is
perished, and yet the branches are vegete and healthy. Secondly, the
fibres of the bark of trees are chiefly longitudinal, resembling roots,
as is beautifully seen in those prepared barks that were lately brought
from Otaheita. Thirdly, in horizontal wounds of the bark of trees, the
fibres of the upper lip are always elongated downwards like roots, but
those of the lower lip do not approach to meet them. Fourthly, if you
wrap wet moss round any joint of a vine, or cover it with moist earth,
roots will shoot out from it. Fifthly, by the inoculation or engrafting
of trees many fruits are produced from one stem. Sixthly, a new tree is
produced from a branch plucked from an old one and set in the ground.
Whence it appears that the buds of deciduous trees are so many annual
plants, that the bark is a contexture of the roots of each individual
bud, and that the internal wood is of no other use but to support them
in the air, and that thus they resemble the animal world in their
individuality.
"The irritability of plants, like that of animals, appears liable to be
increased or decreased by habit; for those trees or shrubs which are
brought from a colder climate to a warmer, put out their leaves and
blossoms a fortnight sooner than the indigenous ones.
"Professor Kalm, in his travels in New York, observes that the apple
trees brought from England blossom a fortnight sooner than the native
ones. In our country, the shrubs that are brought a degree or two from
the north are observed to flourish better than those which come from the
south. The Siberian barley and cabbage are said to grow larger in this
climate than the similar more southern vegetables; and our hoards of
roots, as of potatoes and onions, germinate with less heat in spring,
after they have been accustomed to the winter's cold, than in autumn,
after the summer's heat.
"II. The stamens and pistils of flowers show evident marks of
sensibility, not only from many of the stamens and some pistils
approaching towards each other at the season of impregnation, but from
many of them closing their petals and calyxes during the cold part of
the day. For this cannot be ascribed to irritation, because cold means
a defect of the stimulus of heat; but as the want of accustomed stimuli
produces pain, as in coldness, hunger, and thirst of animals, these
motions of vegetables in closing up their flowers must be ascribed to
the disagreeable sensation, and not to the irritation of cold. Others
close up their leaves during darkness, which, like the former, cannot be
owing to irritation, as the irritating material is withdrawn.
"The approach of the anthers in many flowers to the stigmas, and of the
pistils of some flowers to the anthers, must be ascribed to the passion
of love, and hence belongs to sensation, not to irritation.
"III. That the vegetable world possesses some degree of voluntary powers
appears from their necessity to sleep, which we have shown in Section
XVIII. to consist in the temporary abolition of voluntary power. This
voluntary power seems to be exerted in the circular movement of the
tendrils of the vines, and other climbing vegetables; or in the efforts
to turn the upper surfaces of their leaves, or their flowers, to the
light.
"IV. The associations of fibrous motions are observable in the vegetable
world as well as in the animal. The divisions of the leaves of the
sensitive plant have been accustomed to contract at the same time from
the absence of light; hence, if by any other circumstance, as a slight
stroke or injury, one division is irritated into contraction, the
neighbouring ones contract also from their motions being associated with
those of the irritated part. So the various stamina of the class of
syngenesia have been accustomed to contract together in the evening, and
thence if you stimulate any one of them with a pin, according to the
experiment of M. Colvolo, they all contract from their acquired
associations.
"To evince that the collapsing of the sensitive plant is not owing to
any mechanical vibrations propagated along the whole branch when a
single leaf is struck with the finger, a leaf of it was slit with sharp
scissors, with as little disturbance as possible, and some seconds of
time passed before the plant seemed sensible of the injury, and then the
whole branch collapsed as far as the principal stem. This experiment was
repeated several times with the least possible impulse to the plant.
"V. 1. For the numerous circumstances in which vegetable buds are
analogous to animals, the reader is referred to the additional notes at
the end of 'Botanic Garden,' Part I. It is there shown that the roots of
vegetables resemble the lacteal system of animals; the sap vessels in
the early spring, before their leaves expand, are analogous to the
placental vessels of the foetus; that the leaves of land plants
resemble lungs, and those of aquatic plants the gills of fish; that
there are other systems of vessels resembling the vena portarum of
quadrupeds, or the aorta of fish; that the digestive power of vegetables
is similar to that of animals converting the fluids which they absorb
into sugar;[164] that their seeds resemble the eggs of animals, and
their buds and bulbs their viviparous offspring; and lastly, that the
anthers and stigmas are real animals attached to their parent tree like
polypi or coral insects, but capable of spontaneous motion; that they
are affected with the passion of love, and furnished with powers of
reproducing their species, and are fed with honey like the moths and
butterflies which plunder their nectaries.[165]
"The male flowers of Vallisneria approach still nearer to apparent
animality, as they detach themselves from the parent plant, and float on
the surface of the water to the female ones.[166] Other flowers of the
classes of monoecia and dioecia, and polygamia discharge the
fecundating farina, which, floating in the air, is carried to the stigma
of the female flowers, and that at considerable distances. Can this be
effected by any specific attraction? Or, like the diffusion of the
odorous particles of flowers, is it left to the currents of the winds,
and the accidental miscarriages of it counteracted by the quantity of
its production?
"2. This leads us to a curious inquiry, whether vegetables have ideas of
external things? As all our ideas are originally received by our senses,
the question may be changed to whether vegetables possess any organs of
sense? Certain it is that they possess a sense of heat and cold, another
of moisture and dryness, and another of light and darkness, for they
close their petals occasionally from the presence of cold, moisture, or
darkness. And it has been already shown that these actions cannot be
performed simply from irritation, because cold and darkness are negative
quantities, and on that account sensation, or volition are implied, and
in consequence a sensorium or union of their nerves. So when we go into
the light we contract the iris; not from any stimulus of the light on
the fine muscles of the iris, but from its motions being associated with
the sensation of too much light upon the retina, which could not take
place without a sensorium or centre of union of the nerves of the iris,
with those of vision.[167]
"Besides these organs of sense, which distinguish cold, moisture, and
darkness, the leaves of mimosa, and of dionaea, and of drosera, and the
stamens of many flowers, as of the berbery, and the numerous class of
syngenesia, are sensible to mechanic impact, that is, they possess a
sense of touch, as well as a common sensorium, by the medium of which
their muscles are excited into action. Lastly, in many flowers the
anthers, when mature, approach the stigma, in others the female organ
approaches to the male. In a plant of collinsonia, a branch of which is
now before me, the two yellow stamens are about three-eighths of an inch
high, and diverge from each other at an angle of about fifteen degrees,
the purple style is half an inch high, and in some flowers is now
applied to the stamen on the right hand, and in others to that of the
left; and will, I suppose, change place to-morrow in those, where the
anthers have not yet effused their powder.
"I ask by what means are the anthers in many flowers and stigmas in
other flowers directed to find their paramours? How do either of them
know that the other exists in their vicinity? Is this curious kind of
storge produced by mechanic attraction, or by the sensation of love? The
latter opinion is supported by the strongest analogy, because a
reproduction of the species is the consequence; and then another organ
of sense must be wanted to direct these vegetable amourettes to find
each other, one probably analogous to our sense of smell, which in the
animal world directs the new-born infant to its source of nourishment,
and they may thus possess a faculty of perceiving as well as of
producing odours.
"Thus, besides a kind of taste at the extremity of their roots, similar
to that of the extremities of our lacteal vessels, for the purpose of
selecting their proper food, and besides different kinds of irritability
residing in the various glands, which separate honey, wax, resin, and
other juices from their blood; vegetable life seems to possess an organ
of sense to distinguish the variations of heat, another to distinguish
the varying degrees of moisture, another of light, another of touch, and
probably another analogous to our sense of smell. To these must be added
the indubitable evidence of their passion of love, and I think we may
truly conclude that they are furnished with a common sensorium for each
bud, and that they must occasionally repeat those perceptions, either in
their dreams or waking hours, and consequently possess ideas of so many
of the properties of the external world, and of their own
existence."[168]
FOOTNOTES:
[155] 'Origin of Species,' note on p. xiv.
[156] 'Zoonomia,' vol. i. p. 170.
[157] Miss Seward's 'Memoirs,' &c., p. 491.
[158] See p. 116 of this volume.
[159] 'Zoonomia,' vol. i. p. 184.
[160] 'Zoonomia,' p. 171.
[161] 'Zoonomia,' p. 187.
[162] 'Nature,' March 14 and 21, 1878.
[163] See 'Botanic Garden,' part ii., note on Silene.
[164] 'On the Digestive Powers of Plants.' See Mr. Francis Darwin's
lecture, already referred to.
[165] See 'Botanic Garden, part i., add. note, p. xxxix.
[166] Ibid., part ii., art. "Vallisneria."
[167] See 'Botanic Garden,' part i. cant 3, l. 440.
[168] 'Zoonomia,' vol. i. p. 107.