DARWINISM. 35 



Mr. Wallace criticizes carefully, and as we think 

 successfully, not only the view of Herbert Spencer, 

 but that which has been lately defended by the 

 American school of evolutionists, and the view 

 of Dr. Karl Sempen ; but he is himself clearly 

 inclined to accept the theory of Weismann, which 

 would cut away the ground from all these theories. 

 According to Weismann's theory, the question of 

 heredity is reduced to one of growth. It is 

 only where propagation is asexual that individual 

 characters are handed on. Elsewhere the individual 

 is only the vehicle for a minute portion of the very 

 same germ-plasm, from which the parent was 

 developed, all that is inherited being handed on, 

 while all that is acquired dies with the individual. 

 The individual, however, is a complex result, 

 inheriting as he does the united germ-plasms of 

 both parents, each of which in turn unites the 

 germ-plasms of two grandparents. Diversity of 

 sex becomes then of primary importance as the 

 cause of variation, and the advantage of cross 

 fertilization is obvious. Such a theory, if proved, 

 would be absolutely fatal to the Neo-Lamarckians, 

 and would triumphantly prove that natural selection 

 is the supreme factor in the origin of species. Mr. 

 Wallace, though he does not speak of Weismann's 

 theory as " proved," is evidently willing to accept 

 it as a good working hypothesis ; and, in any 

 case, he is ready to maintain, as against the Neo- 



