DARWINISM ATTACKED. 35 



book that it need not detain us now. But to my mind it is 



one of the most important matters in connection with the 



whole great problem of descent, that is, of 



Does determi- . v . 



nate variation evolution. It is the basic problem of evolu- 

 exlst? tion, for it is the problem of beginnings. 



Selection, isolation, and the like factors are conditions 

 of species-forming; variation is a prerequisite, a sine 

 qua non. True variation must have its causes, and these 

 causes are to be determined before an actual causo-me- 

 chanical explanation of evolution can ever be found. But 

 the determination of the relation of variation to species- 

 forming is certainly the first step now necessary in our 

 search for the basic factors, the real first causes of species 

 change. 



But even in those cases where there may exist unrestricted 



indeterminate fluctuating variation in continuous series ac- 



Whatdoes cording to the law of error, what is it that this 



fluctuating vari- variation really offers natural selection to 



ation offer selec- , . 



tion as a basis for work on ? Remember what natural selection 



g 



species-forming? j s . t ^ e sav j n g o f one or ten by the actual killin 

 of the thousand or ten thousand because in the struggle for 

 existence the variations of the one or ten are of sufficient 

 advantage to have a life-or-death-determining value. Now 

 between any two successive individuals in a series arranged 

 on a basis of the variations in any one character of any one 

 organ or function, the difference is extremely slight, too 

 slight, one is certain, to be, in most cases, of life or death 

 value. But even if one's conception of the absolute inten- 

 sity of the rigour of the personal struggle leads to a 

 logical conception of an absolute advantage in any differ- 

 ence, however slight, in a favourable direction, it is wholly 

 possible that for any other characteristic equally important 

 in the struggle the two individuals may be in exactly reversed 

 position, the one possessing the infinitesimal advantage in 

 strength say, possessing an infinitesimal disadvantage in 



