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Evolution, Old & New, a non-fiction book by Samuel Butler |
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Chapter 13. Philosophy Of Dr. Erasmus Darwin |
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_ CHAPTER XIII. 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. _ |
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