While, however, natural selection as an agent capable of producing racial change is accepted by almost every well-instructed biologist, there are some who are still inclined to give some value to the operation of the Lamarckian transmission of acquired characters. They do not deny that to selection is due by far the most obvious racial changes, and that experimentally the most potent factor in the production of a new variety of a plant or animal is selection. They are, however, inclined to believe that along with this, there may be some transmission of acquired character, only discernible after the lapse of many generations. Darwin himself thought that this was the case; he held that certain racial distinctions were due to the action of the environment on the parents and the transmission of the change thus produced upon their offspring. In his great work upon “The Variation of Animals and Plants under Domestication,”[4] he enumerates some of these. They may be divided roughly into two classes: first, instincts and habits; and, secondly, results of use and disuse. Darwin believed that the trained habits of dogs and horses, the tameness of the rabbit and other domestic animals, were due to the direct and transmitted effects of man’s contact. He held that the large size of the leg and small size of the wing of the domestic as compared with the wild duck are gradually acquired and transmitted by use and disuse. But Darwin, as Huxley points out,[5] was inclined to lay less stress upon the transmission of acquired characters in his later writings; and we find that in the “Origin of Species” he is inclined to abandon them altogether, and accept the position now held by the Neo-Darwinian School of Galton and Weismann. He says (pp. 117, 118), “If under changed conditions of life, a structure, before useful, becomes less useful, its diminution will be favoured, for it will profit the individual not to have its nourishment wasted in building up useless structures.... Thus, I believe, natural selection will tend in the long run to reduce any part of the organism as soon as it becomes through changed habits superfluous.” Just as Darwin himself, as time went on, laid more and more stress upon the importance of selection, and less and less upon the transmission of acquired characters, most naturalists have tended to follow him in the same direction. It may be said, I think, without gainsay, that, since Darwin’s death, the most important and outstanding work done by the biologists has been the uprooting of much of the Lamarckian doctrine, originally held, not without question, however, by Darwin himself. The biologist of to-day is more Darwinian than Darwin, and explains on the Darwinian hypothesis even those cases which had presented difficulties to Darwin’s own mind. _Galton and Weismann._