FULLER QUOTATIONS FROM THE 'ZOONOMIA.'
The following are the passages in the 'Zoonomia' which have the most important bearing on evolution:--
"The ingenious Dr. Hartley, in his work on man, and some other philosophers have been of opinion, that our immortal part acquires during this life certain habits of action or of sentiment which become for ever indissoluble, continuing after death in a future state of existence; and add that if these habits are of the malevolent kind, they must render their possessor miserable even in Heaven. I would apply this ingenious idea to the generation or production of the embryon or new animal, which partakes so much of the form and propensities of its parent.
"Owing to the imperfection of language the offspring is termed a new animal, but is in truth a branch or elongation of the parent, since a part of the embryon-animal is, or was, a part of the parent, and therefore in strict language, cannot be said to be entirely new at the time of its production; and, therefore, it may retain some of the habits of the parent system.
"At the earliest period of its existence the embryon would seem to consist of a living filament with certain capabilities of irritation, sensation, volition, and association, and also with some acquired habits or propensities peculiar to the parents; the former of these are in common with other animals; the latter seem to distinguish or produce the kind of animal, whether man or quadruped, with the similarity of feature or form to the parent."
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Going on to describe the gradual development of the embryo, Dr. Darwin continues:--
"As the want of this oxygenation of the blood is perpetual (as appears from the incessant necessity of breathing by lungs or gills), the vessels become extended by the efforts of pain or desire to seek this necessary object of oxygenation, and to remove the disagreeable sensations which this want occasions."
"The lateral production of plants by wires, while each new plant is thus chained to its parent, and continues to put forth another and another as the wire creeps onward on the ground, is exactly resembled by the tape-worm or tænia, so often found in the bowels, stretching itself in a chain quite from the stomach to the rectum. Linnæus asserts 'that it grows old at one extremity, while it continues to generate younger ones at the other, proceeding ad infinitum like a sort of grass; the separate joints are called gourd worms, and propagate new joints like the parent without end, each joint being furnished with its proper mouth and organs of digestion.'"
"Many ingenious philosophers have found so great difficulty in conceiving the manner of the reproduction of animals, that they have supposed all the numerous progeny to have existed in miniature in the animal originally created; and that these infinitely minute forms are only evolved or distended, as the embryon increases in the womb. This idea, besides its being unsupported by any analogy we are acquainted with, ascribes a greater tenuity to organized matter than we can readily admit; as these included embryons are supposed each of them to consist of the various and complicate parts of animal bodies, they must possess a much greater degree of minuteness than that which was ascribed to the devils which tempted St. Anthony, of whom 20,000 were said to have been able to dance a saraband on the point of the finest needle without incommoding one another."
"I conceive the primordium or rudiment of the embryon as secreted from the blood of the parent to consist of a simple living filament as a muscular fibre; which I suppose to be an extremity of a nerve of locomotion, as a fibre of the retina is an extremity of a nerve of sensation; as, for instance, one of the fibrils which compose the mouth of an absorbent vessel. I suppose this living filament of whatever form it may be, whether sphere, cube, or cylinder, to be endued with the capability of being excited into action by certain kinds of stimulus. By the stimulus of the surrounding fluid in which it is received from the male it may bend into a ring, and thus form the beginning of a tube. Such moving filaments and such rings are described by those who have attended to microscopic animalculæ. This living ring may now embrace or absorb a nutritive particle of the fluid in which it swims; and by drawing it into its pores, or joining it by compression to its extremities, may increase its own length or crassitude, and by degrees the living ring may become a living tube.
"With this new organization, or accretion of parts, new kinds of irritability may commence; for so long as there was but one living organ it could only be supposed to possess irritability; since sensibility may be conceived to be an extension of the effect of irritability over the rest of the system. These new kinds of irritability and of sensibility in consequence of new organization appear from variety of facts in the more mature animals; thus ... the lungs must be previously formed before their exertions to obtain fresh air can exist; the throat, or oesophagus, must be formed previous to the sensation or appetites of hunger and thirst, one of which seems to reside at the upper end and the other at the lower end of that canal."
It seems to me Dr. Darwin is wrong in supposing that the organ must have preceded the power to use it. The organ and its use--the desire to do and the power to do--have always gone hand in hand, the organism finding itself able to do more according as it advanced its desires, and desiring to do more simultaneously with any increase in power, so that neither appetency nor organism can claim precedence, but power and desire must be considered as Siamese twins begotten together, conceived together, born together, and inseparable always from each other. At the same time they are torn by mutual jealousy; each claims, with some vain show of reason, to have been the elder brother; each intrigues incessantly from the beginning to the end of time to prevent the other from outstripping him; each is in turn successful, but each is doomed to death with the extinction of the other.
"So inflamed tendons and membranes, and even bones, acquire new sensations; and the parts of mutilated animals, as of wounded snails and polypi and crabs, are reproduced; and at the same time acquire sensations adapted to their situation. Thus when the head of a snail is reproduced after decollation with a sharp razor, those curious telescopic eyes are also reproduced, and acquire their sensibility to light, as well as their adapted muscles for retraction on the approach of injury.
"With every change, therefore, of organic form or addition of organic parts, I suppose a new kind of irritability or of sensibility to be produced; such varieties of irritability or of sensibility exist in our adult state in the glands; every one of which is furnished with an irritability or a taste or appetency, and a consequent mode of action peculiar to itself.
"In this manner I conceive the vessels of the jaws to produce those of the teeth; those of the fingers to produce the nails; those of the skin to produce the hair; in the same manner as afterwards, about the age of puberty, the beard and other great changes in the form of the body and disposition of the mind are produced in consequence of new developments; for, if the animal is deprived of these developments, those changes do not take place. These changes I believe to be formed not by elongation or distension of primeval stamina, but by apposition of parts; as the mature crab fish when deprived of a limb, in a certain space of time, has power to regenerate it; and the tadpole puts forth its feet after its long exclusion from the spawn, and the caterpillar in changing into a butterfly acquires a new form with new powers, new sensations, and new desires."
"From hence I conclude that with the acquisition of new parts, new sensations and new desires, as well as new powers are produced; and this by accretion to the old ones and not by distension of them. And finally, that the most essential parts of the system, as the brain for the purpose of distributing the powers of life, and the placenta for the purpose of oxygenating the blood, and the additional absorbent vessels, for the purpose of acquiring aliment, are first formed by the irritations above mentioned, and by the pleasurable sensations attending those irritations, and by the exertions in consequence of painful sensations similar to those of hunger and suffocation. After these an apparatus of limbs for future uses, or for the purpose of moving the body in its present natant state, and of lungs for future respiration, and of testes for future reproduction, are formed by the irritations and sensations and consequent exertions of the parts previously existing, and to which the new parts are to be attached.
"The embryon" must "be supposed to be a living filament, which acquires or makes new parts, with new irritabilities as it advances in its growth."
"From this account of reproduction it appears that all animals have a similar origin, viz. a single living filament; and that the difference of their forms and qualities has arisen only from the different irritabilities and sensibilities, or voluntarities, or associabilities, of this original living filament, and perhaps in some degree from the different forms of the particles of the fluids by which it has at first been stimulated into activity."
"All animals, therefore, I contend, have a similar cause of their organization, originating from a single living filament, endued with different kinds of irritabilities and sensibilities, or of animal appetencies, which exist in every gland, and in every moving organ of the body, and are as essential to living organism as chemical affinities are to certain combinations of inanimate matter.
"If I might be indulged to make a simile in a philosophical work, I should say that the animal appetencies are not only perhaps less numerous originally than the chemical affinities, but that, like these latter, they change with every fresh combination; thus vital air and azote, when combined, produce nitrous acid, which now acquires the property of dissolving silver; so that with every new additional part to the embryon, as of the throat or lungs, I suppose a new animal appetency to be produced."
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Here, again, it should be insisted on that neither can the "additional part" precede "the appetency," nor the appetency precede the additional part for long together--the two advance nearly pari passu; sometimes the power a little ahead of the desire, stimulates the desire to an activity it would not otherwise have known; as those who have more money than they once had, feel new wants which they would not have known if they had not obtained the power to gratify them; sometimes, on the other hand, the desire is a little more active than the power, and pulls the power up to itself by means of the effort made to gratify the desire--as those who want a little more of this or that than they have money to pay for, will try all manner of shifts to earn the additional money they want, unless it is so much in excess of their present means that they give up the endeavour as hopeless; but whichever gets ahead, immediately sets to work to pull the other level with it, the getting ahead either of power or desire being exclusively the work of external agencies, while the coming up level of the other is due to agencies that are incorporate with the organism itself. Thus an unusually abundant supply of food, due to causes entirely beyond the control of the individual, is an external agency; it will immediately set power a little ahead of desire. On this the individual will eat as much as it can--thus learning pro tanto to be able to eat more, and to want more under ordinary circumstances--and will also breed rapidly up to the balance of the abundance. This is the work of the agencies incorporate in the organism, and will bring desire level with power again. Famine, on the other hand, puts desire ahead of power, and the incorporate agencies must either bring power up by resource and invention, or must pull desire back by eating less, both as individuals, and as the race, that is to say, by breeding less freely; for breeding is an assimilation of outside matter so closely akin to feeding, that it is only the feeding of the race, as against that of the individual.
I do not think the reader will find any clearer manner of picturing to himself the development of organism than by keeping the normal growth of wealth continually in his mind. He will find few of the phenomena of organic development which have not their counterpart in the acquisition of wealth. Thus a too sudden acquisition, owing to accidental and external circumstances and due to no internal source of energy, will be commonly lost in the next few generations. So a sudden sport due to a lucky accident of soil will not generally be perpetuated if the offspring plant be restored to its normal soil. Again, if the advance in power carry power suddenly far beyond any past desire, or be far greater than any past-remembered advance of power beyond desire--then desire will not come up level easily, but only with difficulty and all manner of extravagance, such as is likely to destroy the power itself. Demand and Supply are also good illustrations.
But to return to Dr. Darwin.
"When we revolve in our minds," he writes, "first the great changes which we see naturally produced in animals after their nativity, as in the production of the butterfly with painted wings from the crawling caterpillar; or of the respiring frog from the subnatant tadpole; from the boy to the bearded man, from the infant girl to the woman,--in both which cases mutilation will prevent due development.
"Secondly, when we think over the great changes introduced into various animals by artificial or accidental cultivation, as in horses, which we have exercised for the different purposes of strength or swiftness, in carrying burthens or in running races, or in dogs which have been cultivated for strength and courage, as the bull-dog; or for acuteness of his sense of smell, as the hound or spaniel; or for the swiftness of his foot, as the greyhound; or for his swimming in the water or for drawing snow sledges, as the rough-haired dogs of the north; or, lastly, as a play dog for children, as the lapdog; with the changes of the forms of the cattle which have been domesticated from the greatest antiquity, as camels and sheep, which have undergone so total a transformation that we are now ignorant from what species of wild animal they had their origin. Add to these the great changes of shape and colour which we daily see produced in smaller animals from our domestication of them, as rabbits or pigeons, or from the difference of climates and even of seasons; thus the sheep of warm climates are covered with hair instead of wool; and the hares and partridges of the latitudes which are long buried in snow become white during the winter months; add to these the various changes produced in the forms of mankind by their early modes of exertion, or by the diseases occasioned by their habits of life, both of which become hereditary, and that through many generations. Those who labour at the anvil, the oar, or the loom, as well as those who carry sedan chairs or who have been educated to dance upon the rope, are distinguishable by the shape of their limbs; and the diseases occasioned by intoxication deform the countenance with leprous eruptions, or the body with tumid viscera, or the joints with knots and distortions.
"Thirdly, when we enumerate the great changes produced in the species of animals before their nativity, as, for example, when the offspring reproduces the effects produced upon the parent by accident or cultivation; or the changes produced by the mixture of species, as in mules; or the changes produced probably by the exuberance of nourishment supplied to the fetus, as in monstrous births with additional limbs; many of these enormities of shape are propagated and continued as a variety at least, if not as a new species of animal. I have seen a breed of cats with an additional claw on every foot; of poultry also with an additional claw, and with wings to their feet; and of others without rumps. Mr. Buffon mentions a breed of dogs without tails which are common at Rome and Naples--which he supposes to have been produced by a custom long established of cutting their tails close off. There are many kinds of pigeons admired for their peculiarities which are more or less thus produced and propagated.
"When we consider all these changes of animal form and innumerable others which may be collected from the books of natural history, we cannot but be convinced that the fetus or embryon is formed by apposition of new parts, and not by the distention of a primordial nest of germs included one within another like the cups of a conjurer.
"Fourthly, when we revolve in our minds the great similarity of structure which obtains in all the warm-blooded animals, as well quadrupeds, birds, and amphibious animals, as in mankind; from the mouse and bat to the elephant and whale; one is led to conclude that they have alike been produced from a similar living filament. In some this filament in its advance to maturity has acquired hands and fingers with a fine sense of touch, as in mankind. In others it has acquired claws or talons, as in tigers and eagles. In others, toes with an intervening web or membrane, as in seals and geese. In others it has acquired cloven hoofs, as in cows and swine; and whole hoofs in others, as in the horse: while in the bird kind this original living filament has put forth wings instead of arms or legs, and feathers instead of hair. In some it has protruded horns on the forehead instead of teeth in the fore part of the upper jaw; in others, tusks instead of horns; and in the others, beaks instead of either. And all this exactly as is seen daily in the transmutation of the tadpole, which acquires legs and lungs when he wants them, and loses his tail when it is no longer of service to him.
"Fifthly, from their first rudiment or primordium to the termination of their lives, all animals undergo perpetual transformations; which are in part produced by their own exertions in consequence of their desires and aversions, of their pleasures and their pains, or of irritations or of associations; and many of these acquired forms or propensities are transmitted to their posterity.
"As air and water are supplied to animals in sufficient profusion, the three great objects of desire which have changed the forms of many animals by their desires to gratify them are those of lust, hunger, and security. A great want of one part of the animal world has consisted in the desire of the exclusive possession of the females; and these have acquired weapons to combat each other for this purpose, as the very thick, shield-like, horny skin on the shoulder of the boar is a defence only against animals of his own species who strike obliquely upwards, nor are his tusks for other purposes except to defend himself, as he is not naturally a carnivorous animal. So the horns of the stag are sharp to offend his adversary, but are branched for the purpose of parrying or receiving the thrust of horns similar to his own, and have therefore been formed for the purpose of combating other stags, for the exclusive possession of the females; who are observed like the ladies in the times of chivalry to attend the car of the victor.
"The birds which do not carry food to their young, and do not therefore marry, are armed with spurs for the purpose of fighting for the exclusive possession of the females, as cocks and quails. It is certain that these weapons are not provided for their defence against other adversaries, because the females of these species are without this armour. The final cause of this contest among the males seems to be that the strongest and most active animal should propagate the species, which should thence become improved."
Dr. Darwin would have been on stronger ground if he had said that the effect of the contest among the males was that the fittest should survive, and hence transmit any fit modifications which had occurred to them as vitally true, rather than that the desire to attain this end had caused the contest; but either way the sentence just given is sufficient to show that he was not blind to the fact that the fittest commonly survive, and to the consequences of this fact. The use, however, of the word "thence," as well as of the expression "final cause," is loose, as Dr. Darwin would no doubt readily have admitted. Improvement in the species is due quite as much, by Dr. Darwin's own showing, to the causes which have led to such and such an animal's making itself the fittest, as to the fact that if fittest it will be more likely to survive and transmit its improvement. There have been two factors in modification; the one provides variations, the other accumulates them; neither can claim exclusive right to the word "thence," as though the modification was due to it and to it only. Dr. Darwin's use of the word "thence" here is clearly a slip, and nothing else; but it is one which brings him for the moment into the very error into which his grandson has fallen more disastrously.
"Another great want," he continues, "consists in the means of procuring food, which has diversified the forms of all species of animals. Thus the nose of the swine has become hard for the purpose of turning up the soil in search of insects and of roots. The trunk of the elephant is an elongation of the nose for the purpose of pulling down the branches of trees for his food, and for taking up water without bending his knees. Beasts of prey have acquired strong jaws or talons. Cattle have acquired a rough tongue and a rough palate to pull off the blades of grass, as cows and sheep. Some birds have acquired harder beaks to crack nuts, as the parrot. Others have acquired beaks to break the harder seeds, as sparrows. Others for the softer kinds of flowers, or the buds of trees, as the finches. Other birds have acquired long beaks to penetrate the moister soils in search of insects or roots, as woodcocks, and others broad ones to filtrate the water of lakes and to retain aquatic insects. All which seem to have been gradually produced during many generations by the perpetual endeavour of the creature to supply the want of food, and to have been delivered to their posterity with constant improvement of them for the purposes required.
"The third great want among animals is that of security, which seems to have diversified the forms of their bodies and the colour of them; these consist in the means of escaping other animals more powerful than themselves. Hence some animals have acquired wings instead of legs, as the smaller birds, for purposes of escape. Others, great length of fin or of membrane, as the flying fish and the bat. Others have acquired hard or armed shells, as the tortoise and the Echinus marinus.
"Mr. Osbeck, a pupil of Linnæus, mentions the American frog-fish, Lophius Histrio, which inhabits the large floating islands of sea-weed about the Cape of Good Hope, and has fulcra resembling leaves, that the fishes of prey may mistake it for the sea-weed, which it inhabits.
"The contrivances for the purposes of security extend even to vegetables, as is seen in the wonderful and various means of their concealing or defending their honey from insects and their seeds from birds. On the other hand, swiftness of wing has been acquired by hawks and swallows to pursue their prey; and a proboscis of admirable structure has been acquired by the bee, the moth, and the humming bird for the purpose of plundering the nectaries of flowers. All which seem to have been formed by the original living filament, excited into action by the necessities of the creatures which possess them, and on which their existence depends.
"From thus meditating on the great similarity of the structure of the warm-blooded animals, and at the same time of the great changes they undergo both before and after their nativity; and by considering in how minute a portion of time many of the changes of animals above described have been produced; would it be too bold to imagine that in the great length of time since the earth began to exist, perhaps millions of ages before the commencement of the history of mankind--would it be too bold to imagine that all warm-blooded animals have arisen from one living filament, which the Great First Cause endued with animality, with the power of attaining new parts, attended with new propensities, directed by irritations, sensations, volitions, and associations; and thus possessing the faculty of continuing to improve, by its own inherent activity, and of delivering down those improvements by generation to its posterity world without end!
"Sixthly, the cold-blooded animals, as the fish tribes, which are furnished with but one ventricle of the heart, and with gills instead of lungs, and with fins instead of feet or wings, bear a great similarity to each other; but they differ nevertheless so much in their general structure from the warm-blooded animals, that it may not seem probable at first view that the same living filament could have given origin to this kingdom of animals, as to the former. Yet are there some creatures which unite or partake of both these orders of animation, as the whales and seals; and more particularly the frog, who changes from an aquatic animal furnished with gills to an aerial one furnished with lungs.
"The numerous tribes of insects without wings, from the spider to the scorpion, from the flea to the lobster; or with wings, from the gnat or the ant to the wasp and the dragon-fly, differ so totally from each other, and from the red-blooded classes above described, both in the forms of their bodies and in their modes of life; besides the organ of sense, which they seem to possess in their antennæ or horns, to which it has been thought by some naturalists that other creatures have nothing similar; that it can scarcely be supposed that this nature of animals could have been produced by the same kind of living filament as the red-blooded classes above mentioned. And yet the changes which many of them undergo in their early state to that of their maturity, are as different as one animal can be from another. As those of the gnat, which passes his early state in water, and then stretching out his new wings and expanding his new lungs, rises in the air; as of the caterpillar and bee-nymph, which feed on vegetable leaves or farina, and at length bursting from their self-formed graves, become beautiful winged inhabitants of the skies, journeying from flower to flower, and nourished by the ambrosial food of honey.
"There is still another class of animals which are termed vermes by Linnæus, which are without feet or brain, and are hermaphrodites, as worms, leeches, snails, shell-fish, coralline insects, and sponges, which possess the simplest structure of all animals, and appear totally different from those already described. The simplicity of their structure, however, can afford no argument against their having been produced from a single living filament, as above contended.
"Last of all, the various tribes of vegetables are to be enumerated amongst the inferior orders of animals. Of these the anthers and stigmas have already been shown to possess some organs of sense, to be nourished by honey, and to have the power of generation like insects, and have thence been announced amongst the animal kingdom in Section XIII.; and to these must be added the buds and bulbs, which constitute the viviparous offspring of vegetation. The former I suppose to be beholden to a single living filament for their seminal or amatorial procreation; and the latter to the same cause for their lateral or branching generation, which they possess in common with the polypus, tænia, and volvox, and the simplicity of which is an argument in favour of the similarity of its cause.
"Linnæus supposes, in the introduction to his natural orders, that very few vegetables were at first created, and that their numbers were increased by their intermarriages, and adds, 'Suaderet hæc Creatoris leges a simplicibus ad composita.' Many other changes appear to have arisen in them by their perpetual contest for light and air above ground, and for food or moisture beneath the soil. As noted in the 'Botanic Garden,' Part II., note on Cuscuta. Other changes of vegetables from climate or other causes are remarked in the note on Curcuma in the same work. From these one might be led to imagine that each plant at first consisted of a single bulb or flower to each root, as the gentianella and daisy, and that in the contest for air and light, new buds grew on the old decaying flower-stem, shooting down their elongated roots to the ground, and that in process of ages tall trees were thus formed, and an individual bulb became a swarm of vegetables. Other plants which in this contest for light and air were too slender to rise by their own strength, learned by degrees to adhere to their neighbours, either by putting forth roots like the ivy, or by tendrils like the vine, or by spiral contortions like the honeysuckle, or by growing upon them like the mistleto, and taking nourishment from their barks, or by only lodging or adhering on them and deriving nourishment from the air as tillandsia.
"Shall we then say that the vegetable living filament was originally different from that of each tribe of animals above described? And that the productive living filament of each of those tribes was different from the other? Or as the earth and ocean were probably peopled with vegetable productions long before the existence of animals; and many families of these animals, long before other families of them, shall we conjecture that one and the same kind of living filament is and has been the cause of all organic life?
"The late Mr. David Hume in his posthumous works places the powers of generation much above those of our boasted reason, and adds, that reason can only make a machine, as a clock or a ship, but the power of generation makes the maker of the machine; and probably from having observed that the greatest part of the earth has been formed out of organic recrements, as the immense beds of limestone, chalk, marble, from the shells of fish; and the extensive provinces of clay, sandstone, ironstone, coals, from decomposed vegetables; all of which have been first produced by generation, or by the secretion of organic life; he concludes that the world itself might have been generated rather than created; that it might have been gradually produced from very small beginnings, increasing by the activity of its inherent principles, rather than by a sudden evolution of the whole by the Almighty fire. What a magnificent idea of the infinite power of the great Architect! The Cause of causes! Parent of parents! Ens entium!"
 'Zoonomia,' vol. i. p. 484.
 Ibid. p. 485.
 Ibid. p. 493.
 'Zoonomia,' vol. i. p. 494.
 'Zoonomia,' vol. i. p. 497.
 'Zoonomia,' vol. i. p. 498.
 'Zoonomia,' vol. i. p. 500.
 Ibid. p. 501.
 Ibid. p. 502.
 'Zoonomia,' vol. i. p. 503.
 'Zoonomia,' vol. i. p. 505.
 'Zoonomia,' vol. i. p. 507.
 'Voyage to China,' p. 113.
 'Zoonomia,' vol. i. p. 511.
 'Zoonomia,' vol. i. p. 513.