Darwin had put forward a theory of heredity which he called “Pangenesis,” which made out a good case for the admission of the Lamarckian factor. According to this theory all the somatic or body cells give forth still smaller cells which he calls “gemmules.” These gemmules are collected, by some process not explained, in the reproductive organs. Here they are in packets, and these “packets of gemmules” are “the carriers of heredity.” One can easily see how by this process the effects of use and disuse would be transmissible for an organ shrunk by disuse would not be capably represented by an efficient delegation of gemmules at the reproductive headquarters. Speaking of this theory, Grant Allen in his biography of Darwin says, “Let not the love of the biographer deceive us. Not to mince matters, it was his one conspicuous failure, and is now pretty universally admitted as such.” It must be remembered however, that Darwin was fully aware of its purely speculative character and with his usual caution entitled it the “Provisional Hypothesis of Pangenesis.” Romanes, one of Weismann’s ablest critics, compares Weismann’s theory with Darwin’s, and while he refuses to defend Pangenesis against Weismann’s charge that it is a wholly unsupported speculation, he replies by contending that the germ-plasm theory lives in precisely the same kind of a glass house. However that may be, it is quite clear that the germ-plasm theory completely shuts out the Lamarckian factor of evolution in all cases where propagation is sexual. “But,” say the Neo-Lamarckians, “Darwinism in itself, merely assumes variations without attempting to explain their origin. Natural selection only explains the survival of the fittest; it tells us nothing of what Prof. Cope calls the ‘Origin of the Fittest.’ There must be variation before selection, whence then, comes this variation?” To this question Weismann has a ready reply. “Variation is due to the blending of two wholly different kinds of germ-plasm at conception, producing at birth a result that is not, and cannot be, wholly like the contributor of either.” And now, at last, the great German is in a corner. If all variations are due to congenital characters only, and these, of course, are only possible because of the combinations secured by sexual reproduction, how do variations arise among non-sexual organisms where such combinations cannot exist?