228 The Science of Life. 



If we take a third cross-section, namely, at the pre- 

 sent day, we find the same diversity as heretofore, but, 

 just as in sections of a developing embryo, the several 

 components are beginning to be more sharply differenti- 

 ated. The Neo-Darwinians are more thorough-going 

 selectionists than Darwin was, and the Neo-Lamarck- 

 ians have added breadth and subtlety to Lamarckism. 

 There are still a few who try to put back the hands of 

 the intellectual clock; but the vast majority would agree 

 with Wallace (1889), that "Darwin did his work so 

 well that ' descent with modification ' is now universally 

 accepted as the order of nature in the organic world ". 

 By its applicability to many different orders of fact, and 

 its continual fruitfulness in research, the evolution- 

 concept justifies itself more and more completely as a 

 modal interpretation of the world around us, and is fast 

 becoming organic in all our thinking. At the same 

 time, while conviction has deepened, the early dogma- 

 tism has disappeared, for the consistent evolutionist 

 recognizes that he and his interpretation, like the world 

 which he studies, are within the sweep of the evolution 

 process, have been evolved, and are still evolving. 

 Therefore he is far from claiming finality of interpre- 

 tation, for that would be a self-contradiction. 



But while the fact of evolution forces itself upon us, 

 certainty in regard to the factors seems as far off as ever. 

 When we remember the complexity of the problem and 

 the relative youthfulness of serious aetiology, the recog- 

 nition of uncertainties is seen as a symptom rather of 

 progress than of any disruption, or perhaps as analo- 

 gous to that histolysis which often precedes organic 

 metamorphosis. And, we would reiterate, the uncer- 

 tainties affect the method of evolution its causes, its 

 factors in nowise the stability of the general idea. 



Among the steps of importance which have been 

 taken of recent years, the following appear outstanding : 



Some Re- ( a ) Weismann's supplement to Darwinism; 



cent steps. (#) Bateson's study of variation ; (c) the 



statistical studies of Weldon, Pearson, and others; (d) 



the inquiry into modes of Isolation; and (e) the theory 



of " organic selection ". 



