No. 484] CLOSELY RELATED SPECIES 



209 



The finely discriminative work of modern taxonomers, much 

 as it confuses and discourages students of other aspects of bio- 

 logic science, is necessary for several reasons but especially is 

 it necessary from the point of view of the evolution problem. 

 Doubtless systematic and experimental work will be more fre- 

 quently cooperative henceforth, and such studies as those of 

 Alexis Jordan, de Bary, Rosen and Wittrock will be repeated 

 with many of the so-called polymorphic plant groups by students 

 of the greater problem. 



This view is apparently opposed to that lately expressed by a 

 prominent worker in experimental evolution, who seems to deny 

 this applicability. "The underlying fault," he says, "consists 

 in the fact that taxonomic and geographic methods are not in 

 themselves, or conjointly, adequate for the analysis, or solution, 

 of genetic problems. The inventor did not reach the solution 

 of the problem of the construction of a typesetting machine by 

 studying the structure of the printed page, but by actual experi- 

 mentation with mechanisms, using printed pages only as a record 

 of his success. Likewise no amount of consideration of fossils, 

 herbarium specimens, dried skins, skulls, or fish in alcohol may 



eration, although from such historical data the general trend 

 or direction of succession may be traced." — MacDougal (:06, 

 p. 4). 



Nevertheless, it may be shown that, while such studies are 

 not in themselves adequate to the solution of genetic problems 

 they have a very high corrective and evaluatory worth. 



Geographic studies foiuided on an exact taxonomy have a 

 corrective function. It is axiomatic that no theory having its 

 origin in experiment can be acccj)tc(l if it seems to be in funda- 

 mental (lisconl with what wc know of the present disposition 

 of the organic world. For example, the theory of MutJition as 

 developed by de Vries cannot be acci^ptnl for the animal king- 

 dom, if, as seems to certain zoolo^M'sts, it is irreconcilable with 

 the facts of the distribution of animals. And even if an hypoth- 

 esis is not positively excluded by the facts, it may be weakened 

 or practically nullified by comparison with large bodies of facts 



