214 Experime7ital Zoology 



anatomy, embryology, and paleontology. Charles Darwin 

 occupies a unique position. Like his predecessors, he argued 

 for the theory of evolution on the basis of comparative anatomy 

 and paleontology, but in addition he brought forward his theory 

 of natural selection to account for the "origin of species," as 

 the result of the survival of the individuals that are better 

 adapted. In support of his theory of natural selection he 

 introduced the evidence from artificial selection as carried out 

 by man. Here almost for the first time the experimental study 

 of evolution was begun. Darwin's more immediate followers, 

 however, did not carry on the experimental work much beyond 

 the stage at which he left it. In the last decade, however, great 

 activity has begun along experimental lines with most promising 

 results, and at the present time the study of evolution has passed 

 into an experimental stage. 



The results that de Vries has obtained with plants in his experi- 

 mental garden have opened a new era in the study of evolution, 

 for he has shown that the process may not be so slow that it can 

 only be detected by elaborate mathematical calculations, or at 

 least that it may at times be rapid and easily detected; and, 

 what is more important, he has shown that this process is going 

 on at the present time. De Vries's results will be described later, 

 and his evidence compared with that obtained by zoologists for 

 animal forms; but before taking up de Vries's work, certain 

 other considerations must first be dealt with. 



The Analogy with Artificial Selection 



If, as Darwin supposed, the domesticated races have been 

 formed largely by the selection of fluctuating variations, a strong 

 argument, at least, would have been estabhshed in favor of an 

 analogous method in nature having produced wild species; but 

 it is probable that Darwin rehed too extensively on the statements 

 of breeders and amateurs as to the process by which their resuhs 

 were obtained. It is clear that many of these breeders lack the 

 scientific training and appreciation of the value of evidence to 

 make their conclusions trustworthy, and however interesting 



