Another important factor in the evolution of the metazoa or many-celled animals, from the sponges and polyps upward from the one-celled forms or protozoa, is the principle of animal aggregation or colonization advanced by Professor Perrier. As civilization and progressive intelligence in mankind arose from the aggregation of men into tribes or peoples which lived a sedentary life, so the agricultural, building, and other arts forthwith sprang up; and as the social insects owe their higher degree of intelligence to their colonial mode of life, so as soon as unicellular organisms began to become fixed, and form aggregates, the sponge and polyp types of organization resulted, this leading to the gastræa, or ancestral form from which all the higher phyla may have originated.
M. Perrier appears to fully accept Lamarck’s views, including his speculations as to wants, and use and disuse. He, however, refuses to accept Lamarck’s extreme view as to the origin through effort of entirely new organs. As he says: “Unfortunately, if Lamarck succeeded in explaining in a plausible way the modification of organs already existing, their adaptation to different uses, or even their disappearance from disuse, in regard to the appearance of new organs he made hypotheses so venturesome that they led to the momentary forgetfulness of his other forceful conceptions.”[250]
The popular idea of Lamarckism, and which from the first has been prejudicial to his views, is that an animal may acquire an organ by simply wishing for or desiring it, or, as his French critics put it, “Un animal finit toujours par posséder un organe quand il le veut.” “Such,” says Perrier,[251] “is not the idea of Lamarck, who simply attributes the transformations of species to the stimulating action of external conditions, construing it under the expression of wants (besoins), and explaining by that word what we now call adaptations. Thus the long neck of the giraffe results from the fact that the animal inhabits a country where the foliage is situated at the tops of high trees; the long legs of the wading birds have originated from the fact that these birds are obliged to seek their food in the water without wetting themselves,” etc. (See p. 350.)
“Many cases,” says Perrier, “may be added to-day to those which Lamarck has cited to support his first law [pp. 303, 346]; the only point which is open to discussion is the extent of the changes which an organ may undergo, through the use it is put to by the animal. It is a simple question of measurement. The possibility of the creation of an organ in consequence of external stimuli is itself a matter which deserves to be studied, and which we have no right to reject without investigation, without observations, or to treat as a ridiculous dream; Lamarck would doubtless have made it more readily accepted, if he had not thought it well to pass over the intermediate steps by means of wants. It is incontestable that by lack of exercise organs atrophy and disappear.”
Finally, says Perrier: “Without doubt the real mechanism of the improvement (perfectionnement) of organisms has escaped him [Lamarck], but neither has Darwin explained it. The law of natural selection is not the indication of a process of transformation of animals; it is the expression of the total results. It states these results without showing us how they have been brought about. We indeed see that it tends to the preservation of the most perfect organisms; but Darwin does not show us how the organisms themselves originated. This is a void which we have only during these later years tried to fill” (p. 90).
Dr. J. A. Jeffries, author of an essay “On the Epidermal System of Birds,” in a later paper[252] thus frankly expresses his views as to the relations of natural selection to the Lamarckian factors. Referring to Darwin’s case of the leg bones of domestic ducks compared with those of wild ducks, and the atrophy of disused organs, he adds:
“In this case, as with most of Lamarck’s laws, Darwin has taken them to himself wherever natural selection, sexual selection, and the like have fallen to the ground.
“Darwin’s natural selection does not depend, as is popularly supposed, on direct proof, but is adduced as an hypothesis which gains its strength from being compatible with so many facts of correlation between an organism and its surroundings. Yet the same writer who considers natural selection proved will call for positive experimental proof of Lamarck’s theory, and refuse to accept its general compatibility with the facts as support. Almost any case where natural selection is held to act by virtue of advantage gained by use of a part is equally compatible with Lamarck’s theory of use and development. The wings of birds of great power of flight, the relations of insects to flowers, the claws of beasts of prey, are all cases in point.”
Professor J. A. Thomson’s useful Synthetic Summary of the Influence of the Environment upon the Organism (1887) takes for its text Spencer’s aphorism, that the direct action of the medium was the primordial factor of organic evolution. Professor Geddes relies on the changes in the soil and climate to account for the origin of spines in plants.
The botanist Sachs, in his Physiology of Plants (1887), remarks: “A far greater portion of the phenomena of life are [is] called forth by external influences than one formerly ventured to assume.”
Certain botanists are now strong in the belief that the species of plants have originated through the direct influence of the environment. Of these the most outspoken is the Rev. Professor G. Henslow. His view is that self-adaptation, by response to the definite action of changed conditions of life, is the true origin of species. In 1894[253] he insisted, “in the strictest sense of the term, that natural selection is not wanted as an ‘aid’ or a ‘means’ in originating species.” In a later paper[254] he reasserts that all variations are definite, that there are no indefinite variations, and that natural selection “can take no part in the origination of varieties.” He quotes with approval the conclusion of Mr. Herbert Spencer in 1852, published
“seven years before Darwin and Dr. Wallace superadded natural selection as an aid in the origin of species. He saw no necessity for anything beyond the natural power of change with adaptation; and I venture now to add my own testimony, based upon upwards of a quarter of a century’s observations and experiments, which have convinced me that Mr. Spencer was right and Darwin was wrong. His words are as follows: ‘The supporters of the development hypothesis can show ... that any existing species, animal or vegetable, when placed under conditions different from its previous ones, immediately begins to undergo certain changes of structure fitting it for the new conditions; ... that in the successive generations these changes continue until ultimately the new conditions become the natural ones.... They can show that throughout all organic nature there is at work a modifying influence of the kind they assign as the causes of specific differences; an influence which, though slow in its action, does in time, if the circumstances demand it, produce marked changes.’”[255]