l8o SCIENCE SKETCHES. 



will be made by different minds. That this, how- 

 ever, is one of the great controlHng factors in the 

 production of diversity in the Hfe of the earth, 

 cannot be questioned. 



Darwin's work was addressed at first only to 

 naturalists, with no expectation that the public 

 would pay any attention to it. He had confidence 

 that the younger and more observant of his fellow- 

 workers would find in their own work confirmation 

 of his conclusions. The times were riper than he 

 had dreamed. He has outlived nearly all of his 

 scientific opponents, the greatest and perhaps the 

 last of whom was Agassiz. To-day there is not one 

 whose scientific studies have been such as to give 

 him a right to speak, whose views are not in sub- 

 stantial accord with those of the *' Origin of Spe- 

 cies." ^ Darwin's work has destroyed forever the 

 closet-formed idea of a *' species " in biology as 

 something fundamentally different from a variety 

 or a race. 



Let me take an illustration. Camille Dareste, 

 writing of the hundred or more alleged species of 

 the True Eel (^Anguilld) says : — 



" There are at least four distinct types, resulting from 

 the combination of a certain number of characters ; but 



1 I say this advisedly. I know that some half dozen geologists 

 and biologists of high repute still hold to the dogma of the immu- 

 tability of species. Not one of these, so far as I know, has ever 

 made any serious special study of species in any group, — of their 

 relations to each other, their variations, their embryology or their 

 geographical distribution. 1 cannot see how one who has not done 

 this has any right to believe that species are practically unchange- 

 able in face of the almost unanimous testimony of all who have 

 made such matters a life-study. 



