136 HUMANISM vm 



work on the subject l it very distinctly suggests that 

 variation is frequently discontinuous, and that it is to 

 these discontinuous sports rather than to the accumula 

 tion of slight differences that we have to look for the 

 origin of many new species. 



In both these respects, then, the non - Darwinian 

 evolutionists seek to penetrate deeper into the nature of 

 Organic Evolution than Darwin needed to do when he 

 established the reality and importance of Natural Selection, 

 and when Darwin s followers speak of the omnipotence of 

 Natural Selection, they fail to observe that their opponents 

 have really turned their flank. For while they do not 

 deny the reality of Natural Selection, they go on to solve 

 problems which, on the basis of Darwinism, cannot be 

 discussed. Hence the Darwinians have not really any 

 logical locus standi e.g., in many of their objections to the 

 Lamarckian factors in evolution. Biologists must be 

 left a free hand in their attempts to determine the nature 

 and source of the variations actually occurring, and in 

 their theories to account for them. If, after admitting 

 the existence of natural selection, they go on to say 

 that variations are not indefinite and their causes not in 

 determinable, Darwinian orthodoxy has no right to interfere. 

 Or if it mistakenly does try to interfere, its defeat is certain. 

 For it is practically certain that some influences which 

 can only be called Lamarckian must affect both the 

 number and the character of the variations. Living 

 organisms are subject to the general physical and 

 chemical laws of nature, and these render variations in 

 certain directions practically impossible. It is very 

 probable also that they produce certain definite effects 

 upon the organisms exposed to them, and thus give a 

 definite direction to variation. Thus the force of gravity 

 imposes limits on the size to which organisms can grow 

 upon the earth ; high and low temperatures produce 

 definite effects upon all living tissue. Starvation also will 

 stunt the growth of all organisms. The efficacy, then, of 

 these additional factors in determining both what sort of 



1 Materials for the Study of Variation. 



