434 ANNALS NEW YORK ACADEMY OF SCIENCES 



not proved, nor even probable, that cultivated plants are intrinsically more 

 variable than their wild prototypes." ^ As to distinct mutations, we must 

 remember that plants and animals preserved and nurtured by man are 

 constantly under the eyes of many thousands of pecuniarily interested ob- 

 servers, while those in a state of nature are closely studied by but a handful 

 of scientific investigators. We must also remember that it is only within a 

 few years that a small fraction of these men of science have been led to look 

 for cases of mutation, while all gardeners, farmers and breeders have had 

 the inducement of financial profit to watch for marked variations among their 

 stock and to preserve such variations if desirable. The naturalists specially 

 interested in evolutionary questions are exceedingly few in number, but their 

 field of research is immensely extended and varied. The number of those 

 who have raised animals and plants for gain, however, has always been 

 large, though the number of forms which they have been called upon to 

 consider have been relatively few. The two fields have consequently had 

 exceedingly different degrees of scrutiny. But since de Vries and others 

 opened up the subject an astonishing number of clearly proven cases of 

 mutation has been discovered in very various classes of organisms, just as 

 numerous paleontological evidences of evolution have been brought to light 

 as a consequence of Darwin's turning men's minds in that direction. 



As I have already intimated, Mr. Darwin undoubtedly dealt with num- 

 erous cases of mutation among domesticated animals and plants, and they 

 gave him little or no intellectual disquietude. In his work on "Animals 

 and Plants Under Domestication," he gives a long catalogue of "spontane- 

 ous variations" or "sports," many of which he freely acknowledges were 

 the starting points of new and constant races; and there is good reason to 

 believe that some of them occurred before the animals and plants which 

 underwent the sudden changes had been actually brought under domestica- 

 tion and cultivation; in fact that the mutations themselves suggested to men 

 the directions in which their breeding operations should be conducted. For 

 example, take the case of the tumbler pigeon ; Mr. Darwin remarks concern- 

 ing this that "no one would ever have thought of teaching, or probably 

 could have taught, the tumbler pigeon to tumble,"" but it seems to me 

 obvious that no one would ever have thought of accumulating slight varia- 

 tions in the direction of tumbling. It is much more reasonable to suppose 

 that the birds which were artificially selected as the progenitors of the present 

 race of tumbler pigeons actually tumbled — tfeat is to say, they were mutants. 

 As to the origin of domestic races through modifications so abrupt as to 



1 " Species and Varieties, their Origin by Mutation," 2d ed., 1906, p. 66. 

 2" Origin of Species," 6tli ed., 1882, p. 210. 



