190 



THE AMEBIC AN NATURALIST [Vol. XL VI 



in Darwin's mind as to whether "the selection of muta- 

 tions' ' or "the selection of extreme variants" played 

 the greater part in the origin of species. As above noted, 

 the actual cases which Darwin cited and his repeated 

 emphasis shows that minor saltations of the De Vries 

 type were chiefly in his mind. 



It is obvious that Darwin could not draw such sharp 

 distinctions either in language or in definition as we may 

 to-day, profiting by forty years of experiment and of 

 analysis. 



Let us therefore closely examine the kinds of saltation 

 or discontinuity in mammals which have been recorded 

 during the last fifty years by Darwin, Bateson and others 

 and see what they signify. 



1. Major and Minor Saltations in Mammals as Supposed 

 Material for Selection* 

 The above exposition of Darwin has a very direct bear- 

 ing on the problem of continuity and discontinuity be- 

 cause the saltations which he believed to be among the 

 possible materials of natural selection and of evolution 

 were chiefly drawn from the very same sources of evi- 

 dence, namely, hybridization and artificial conditions of 

 environment, which are now drawn upon by the ad- 

 herents of discontinuity; the only difference is one of 

 degree, not of kind. The great saltatory characters of 

 Darwin cited below (Table I) in mammals are no more 

 profound than those cited by De Vries as composing the 

 supposed "elementary" species of (Enothera. It is 

 therefore interesting to compare twenty distinct types or 

 forms of major and minor saltation in eleven different 

 types of mammals. Our authorities are Allen, Azara, 

 Bateson, Brinkerhoff, Castle, Darwin, Davenport, 

 Haecker, Percival, Poulton, Eidgeway, Root, Seton, Sut- 

 ton, Twining. The accompanying table presents at once 

 the very impressive result obtained by this comparison. 



8 The writer is greatly indebted to Dr. Charles B. Davenport, of the 



