i/6 THE POPULAR SCIENCE MONTHLY. 



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, f 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 argu- 

 ment 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 com- 

 plex 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 environ- 

 ment may be regarded as constantly impinging, so as to bring 

 about perpetual modifications. 



In the second volume of his Essays there are further conces- 

 sions in this same general direction. In his reply to Prof. Vines, 

 he is compelled to admit that variation may take place in differ- 

 ent forms of asexual reproduction, which is a practical abandon- 

 ment of his theory of the continuity i. e., of the unalterable na- 

 ture 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." J 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. 



* Neo-Darwinism, etc., p. 58. 



f The Germ-Plasm : A Theory of Heredity. By August Weismann. Translated by W. 

 Newton Parker and Harriet Ronnfeldt. New York: Charles Scribner's Sons, 1893. Con- 

 temporary Science Series. See p. 408. 



\ Essays, vol. ii, p. 95. 



