XIV FUNDAMEXTAL PROBLEMS 443 



Concludinrj Bemarhs. 



Having now jDassed in review the more important of the 

 recent objections to, or criticisms of, the theory of natural 

 selection, we have arrived at the conclusion that in no one 

 case have the writers in question been able materially to 

 diminish its importance, or to show that any of the laws or 

 forces to which they appeal can act otherwise than in strict 

 subordination to it. The direct action of the environment as 

 set forth by Mr. Herbert Spencer, Dr. Cope, and Dr. Karl 

 Semper, even if we admit that its effects on the individual 

 are transmitted by inheritance, are so small in comparison 

 with the amount of spontaneous variation of every part of 

 the organism that they must be quite overshadowed by the 

 latter. And if such direct action may, in some cases, have 

 initiated certain organs or outgrowths, these must from their 

 very first beginnings have been subject to variation and 

 natural selection, and their further development have been 

 almost wholly due to these ever-present and powerful causes. 



Francis Galton's Theory of Heredity (already referred to at p. 417) which 

 was published thirteen years ago as an alternative for Darwin's theory of 

 pangenesis. 



Mr. Galton's theory, although it attracted little attention, appears to me 

 to be substantially the same as that of Professor "VVeismanu. Galton's 

 " stirp " is Weismaim's "germ-plasm." Gallon supposes tln^ sexual elements 

 in the offspring to be directly formed from the residue of the stirp not used 

 up in the development of the body of the parent — Weismann's " continuity 

 of the germ-plasm." Galton also draws many of the same conclusions from 

 his theory. He maintains that characters acquired by the individual as the 

 result of external influences cannot be inherited, unless such influences act 

 directly on the reproductive elements — instancing the possible heredity of 

 alcoholism, because the alcohol permeates the tissues and may reach the 

 sexual elements. He discusses the supposed heredity of effects produced by 

 use or disuse, and explains them much in the same manner as does Weismann. 

 Galton is an anthropologist, and applies the theory, mainly, to exiDlaiu the 

 peculiarities of hereditary transmission in man, many of which peculiarities 

 he discusses and elucidates. Weismann is a biologist, and is mostly concerned 

 with the application of the theory to explain variation and instinct, and to 

 the further development of the theory of evolution. He has worked it out 

 more thoroughly, and has adduced embryological evidence in its support ; but 

 the views of both A\Titers are substantially the same, and their theories were 

 arrived at quite independently. The names of Galton and Weismann should 

 therefore be associated as discoverers of what may be considered (if finally 

 established) the most important contribution to the evolution theory since the 

 appearance of the Origin of Species. 



