Page:Popular Science Monthly Volume 45.djvu/190

176 course, all modifications must first affect the germ, otherwise there could be no hereditary transmission. The only question is: Can the climate or the environment impress changes upon the germ? If yes, the Neo-Lamarckian asks no more. All that he contends for is conceded."

In his later work on the Germ-Plasm, Prof. Weismann says that I am in error if I suppose that "the proof that climatic influences are capable of modifying the germ-plasm contains all that is required by the Neo-Lamarckian school." It is true that climatic influences in the restricted sense are not the only ones that Neo-Lamarckians suppose to act directly upon the germ. They maintain that functional variations are heritable to a greater or less degree, and make the chief distinction between these and accidental variations, such as mutilations and other injuries. The principal stress has hitherto been and still continues to be laid, by both Prof. Weismann and his followers, upon the latter class, which is therefore a waste of words and a mere show of argument calculated to deceive those who have little acquaintance with the subject. But when it comes to modifications of form which are brought about by the efforts and struggles of the creature to obtain its sustenance or accomplish desired ends, the case is wholly different. Such modifications are necessarily complex and involve a harmonious adjustment of all the parts that are brought into exercise, which, when transmitted, secures the complete and systematic variation which species are believed to undergo. Climatic influences are among the most important ones against which the creature thus reacts, but the entire environment may be regarded as constantly impinging, so as to bring about perpetual modifications.

In the second volume of his Essays there are further concessions in this same general direction. In his reply to Prof. Vines, he is compelled to admit that variation may take place in different forms of asexual reproduction, which is a practical abandonment of his theory of the continuity—i. e., of the unalterable nature—of the germ-plasm. He is apparently willing to "concede that some amount of individual variability can be called forth by direct influences on the germ-plasm." Surely a discussion as to the "amount" of such variation is a radically different thing from a discussion as to whether it can take place at all. The principle at issue is shifted when such an admission is made.