“By a rearrangement of the materials of his argument, however, we obtain, as I conceive, convincing proof that external conditions can exert not only a very powerful selective force, but a transforming one as well, although it must be the more limited of the two.
“An organ no longer needed for its original purpose may adapt itself to the altered circumstances, and alter correspondingly if it contains within itself, as I have explained above, the elements of such a change. Then the influence exerted by the changed conditions will be transforming, not selective.
“This last view may seem somewhat bold to those readers who know that Darwin, in his theory of selection, has almost entirely set aside the direct transforming influence of external circumstances. Yet he seems latterly to be disposed to admit that he had undervalued the transforming as well as the selective influence of external conditions; and it seems to me that his objection to the idea of such an influence rested essentially on the method of his argument, which seemed indispensable for setting his theory of selection and his hypothesis as to the transformation of species in a clear light and on a firm footing” (p. 37).
Dr. H. de Varigny has carried on much farther the kind of experiments begun by Semper. In his Experimental Evolution he employs the Lamarckian factors of environment and use and disuse, regarding the selective factors as secondary.
The Lamarckian factors are also depended upon by the late Professor Eimer in his works on the variation of the wall-lizard and on the markings of birds and mammals (1881–88), his final views being comprised in his general work.[240] The essence of his point of view may be seen by the following quotation:
“According to my conception, the physical and chemical changes which organisms experience during life through the action of the environment, through light or want of light, air, warmth, cold, water, moisture, food, etc., and which they transmit by heredity, are the primary elements in the production of the manifold variety of the organic world, and in the origin of species. From the materials thus supplied the struggle for existence makes its selection. These changes, however, express themselves simply as growth” (p. 22).
In a later paper[241] Eimer proposes the term “orthogenesis,” or direct development, in rigorous conformity to law, in a few definite directions. Although this is simply and wholly Lamarckism, Eimer claims that it is not, “for,” he strangely enough says, “Lamarck ascribed no efficiency whatever to the effects of outward influences on the animal body, and very little to their effects upon vegetable organisms.” Whereas if he had read his Lamarck carefully, he would have seen that the French evolutionist distinctly states that the environment acts directly on plants and the lower animals, but indirectly on those animals with a brain, meaning the higher vertebrates. The same anti-selection views are held by Eimer’s pupil, Piepers,[242] who explains organic evolution by “laws of growth, ... uncontrolled by any process of selection.”
Dr. Cunningham likewise, in the preface to his translation of Eimer’s work, gives his reasons for adopting Neolamarckian views, concluding that “the theory of selection can never get over the difficulty of the origin of entirely new characters;” that “selection, whether natural or artificial, could not be the essential cause of the evolution of organisms.” In an article on “The New Darwinism” (Westminster Review, July, 1891) he claims that Weismann’s theory of heredity does not explain the origin of horns, venomous teeth, feathers, wings of insects, or mammary glands, phosphorescent organs, etc., which have arisen on animals whose ancestors never had anything similar.
Discussing the origin of whales and other aquatic mammals, W. Kükenthal suggests that the modifications are partially attributable to mechanical principles. (Annals and Mag. Nat. Hist., February, 1891.)
From his studies on the variation of butterflies, Karl Jordan[243] proposes the term “mechanical selection” to account for them, but he points out that this factor can only work on variations produced by other factors. Certain cases, as the similar variation in the same locality of two species of different families, but with the same wing pattern, tell in favor of the direct action of the local surroundings on the markings of the wings.
In the same direction are the essays of Schroeder[244] on the markings of caterpillars, which he ascribes to the colors of the surroundings; of Fischer[245] on the transmutations of butterflies as the result of changes of temperature, and also Dormeister’s[246] earlier paper. Steinach[247] attributes the color of the lower vertebrates to the direct influence of the light on the pigment cells, as does Biedermann.[248]
In his address on evolution and the factors of evolution, Professor A. Giard[249] has given due credit to Lamarck as “the creator of transformism,” and to the position to be assigned to natural selection as a secondary factor. He quotes at length Lamarck’s views published in 1806. After enumerating the primary factors of organic evolution, he places natural selection among his secondary factors, such as heredity, segregation, amixia, etc. On the other hand, he states that Lamarck was not happy in the choice of the examples which he gave to explain the action of habits and use of parts. “Je ne rappellerai par l’histoire tant de fois critique du cou de la giraffe et des cornes de l’escargot.”