On the other hand, can we in the higher vertebrates entirely dissociate the emotional and mental activities from their physiological or instinctive acts? Mr. Darwin, in his Expressions of the Emotions in Man and Animals, discusses in an interesting and detailed way the effects of the feelings and passions on some of the higher animals.
It is curious, also, that Dr. Erasmus Darwin went at least as far as Lamarck in claiming that the transformations of animals “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.”
Cope, in the final chapter of his Primary Factors of Organic Evolution, entitled “The Functions of Consciousness,” goes to much farther extremes than the French philosopher has been accused of doing, and unhesitatingly attributes consciousness to all animals. “Whatever be its nature,” he says, “the preliminary to any animal movement which is not automatic is an effort.” Hence he regards effort as the immediate source of all movement, and considers that the control of muscular movements by consciousness is distinctly observable; in fact, he even goes to the length of affirming that reflex acts are the product of conscious acts, whereas it is plain enough that reflex acts are always the result of some stimulus.
Another case mentioned by Lamarck in his Animaux sans Vertèbres, which has been pronounced as absurd and ridiculous, and has aided in throwing his whole theory into disfavor, is his way of accounting for the development of the tentacles of the snail, which is quoted on p. 348.
This account is a very probable and, in fact, the only rational explanation. The initial cause of such structures is the intermittent stimulus of occasional contact with surrounding objects, the irritation thus set up causing a flow of the blood to the exposed parts receiving the stimuli. The general cause is the same as that concerned in the production of horns and other hard defensive projections on the heads of various animals.
In commenting on this case of the snail, Professor Cleland, in his just and discriminating article on Lamarck, says:
“However absurd this may seem, it must be admitted that, unlimited time having been once granted for organs to be developed in series of generations, the objections to their being formed in the way here imagined are only such as equally apply to the theory of their origin by natural selection.... In judging the reasonableness of the second law of Lamarck [referring to new wants, see [p. 346]] as compared with more modern and now widely received theories, it must be observed that it is only an extension of his third law; and that third law is a fact. The strengthening of the blacksmith’s arm by use is proverbially notorious. It is, therefore, only the sufficiency of the Lamarckian hypothesis to explain the first commencement of new organs which is in question, if evolution by the mere operation of forces acting in the organic world be granted; and surely the Darwinian theory is equally helpless to account for the beginning of a new organ, while it demands as imperatively that every stage in the assumed hereditary development of an organ must have been useful.... Lamarck gave great importance to the influence of new wants acting indirectly by stimulating growth and use. Darwin has given like importance to the effects of accidental variations acting indirectly by giving advantage in the struggle for existence. The speculative writings of Darwin have, however, been interwoven with a vast number of beautiful experiments and observations bearing on his speculations, though by no means proving his theory of evolution; while the speculations of Lamarck lie apart from his wonderful descriptive labors, unrelieved by intermixture with other matters capable of attracting the numerous class who, provided they have new facts set before them, are not careful to limit themselves to the conclusions strictly deducible therefrom. But those who read the Philosophie Zoologique will find how many truths often supposed to be far more modern are stated with abundant clearness in its pages.” (Encyc. Brit., art. “Lamarck.”)
| Buffon (1761–1778). | Erasmus Darwin (1790–1794). | Lamarck (1801–1809–1815). | Geoffroy St. Hilaire (1795–1831). | Charles Darwin (1859). |
|---|---|---|---|---|
| All animals possibly derived from a single type. | All animals derived from a single filament. | All organisms arose from germs. First germ originated by spontaneous generation. Development from the simple to the complex. Animal series not continuous, but tree-like; graduated from monad to man; constructed the first phylogenetic tree. | Unity of organization in animal kingdom. | |
| Time, its great length, stated. | Time, great length of, definitely demanded. | Time, great length of, definitely postulated; its duration practically unlimited. | Change of “milieu ambiant,” direct. | |
| Immutability of species stated and then denied. | Uniformitarianism of Hutton and of Lyell anticipated. | Founded the doctrine of homologies. | ||
| Nature advances by gradations, passing from one species to another by imperceptible degrees. | Founder of teratology. | Universal tendency to fortuitous variability assumed. | ||
| Changes in distribution of land and water as causing variation. | His embryological studies influenced his philosophic views. | |||
| Effects of changes of climate, direct. | Effects of change of climate, direct (briefly stated). | Effects of favorable circumstances, such as changes of environment, climate, soil, food, temperature; direct in case of plants and lowest animals, indirect in case of the higher animals and man. | ||
| Effects of changes of food. | Conditions of existence remaining constant, species do not vary and vice-versa. | Struggle for existence. | ||
| Effects of domestication. | Domestication briefly referred to. | Struggle for existence; stronger devour the weaker. Competition stated in case of ai or sloth. Balance of nature. | Competition strongly advocated. | |
| Effects of use. (The only examples given are the callosities on legs of camel, of baboon, and the thickening by use of soles on man’s feet.) | Effects of use: characters produced by their own exertions in consequence of their desires, aversions, lust, hunger, and security. | Effects of use and disuse, discussed at length. | Natural selection. | |
| Sexual selection, law of battle. | Vestigial structures the remains of organs actively used by ancestors of present forms. | Sexual selection. | ||
| Protective mimicry. | New wants or necessities induced by changes of climate, habitat, etc., result in production of new propensities, new habits, and functions. | Effects of use and disuse (in some cases). | ||
| Origin of organs before development of their functions. | Change of habits originate organs; change of functions create new organs; formation of new habits precede the origin of new or modification of organs already formed. | Effects of use and disuse (in some cases). | ||
| Geographical isolation suggested as a factor in case of man. | Isolation “an important element.” | |||
| Swamping effects of crossing. Lamarck’s definition of species the most satisfactory yet stated. | Species are “different modifications of one and the same type.” | |||
| Inheritance of acquired characters (vaguely stated). | Inheritance of acquired characters. | Inheritance of acquired characters. | ||
| Instincts result of imitation. | Instinct the result of inherited habits. | |||
| Opposed preformation views of Haller and Bonnet. | Opposed preformation views; epigenesis definitely stated and adopted. |
FOOTNOTES:
[179] [Cabanis.] Rapp. du Phys. et du Moral de l’Homme, pp. 38 à 39, et 85.