No. 496] ASPECTS OF THE SPECIES QUESTION 



by descent as opposed to origin by special creation. For 

 this purpose, it was unnecessary as well as impossible 

 to define a species or to discover the method by Which 

 it originates. Darwin regularly used the terms species, 

 subspecies and variety, but he did not draw a definite and 

 constant line between them. De Vries has taken the 

 first definite step in advance by the use of experiment 

 to determine a species. It remains to be seen whether 

 his concept of elementary species will clarify or confuse. 

 It can not be accepted even provisionally until much 

 more experimental work lias been done. 



In the last decade or two, conservative American botan- 

 ists have often expressed the view that proper specific 

 characters can be drawn only from the flower and fruit, 

 or from the reproductive parts, whatever they may be. 

 Since this has sometimes been said to have been Dr. 

 Gray's view also, it seemed that it would be both profit- 

 able and interesting to compare the criteria of conserva- 

 tive and radical describers of species in the same family 

 and genus. Time was lacking for a thorough and com- 

 plete comparison, but in the few families selected the re- 

 sults seem representative. It was quickly seen that 

 many current species accepted by all were not based upon 

 reproductive characters, and that some of the most doubt- 

 ful of recent ones were. It further appeared that, while 

 habit, leaf, stem, etc., played slightly more important 

 parts in later work, there was little essential difference 

 in the kind of criteria used. The striking difference lay 

 in the fact that the new species segregated are based upon 

 much smaller variations of the parts concerned, as a 

 rule, and are consequently much more difficult to distin- 

 guish when represented by many individuals. 



The ecologist finds it a necessity to be able to distin- 

 guish and to refer to any difference represented by a 

 number of individuals. A form or a variation is just 

 as important to him as a species, and often presents a 

 better point of attack. He must consequently be partly in 

 sympathy with the present tendency of descriptive bot- 



