88 University of California Publications in Zoology. [Vol.6 



6. TO WHAT EXTENT ARE THE SPECIFIC DIFFERENCES BETWEEN 



H. johnsoni and its neighbor H. haustor adaptive? 



That the animal is "in a general way" fitted to the conditions 

 under which it lives is obvious. The proof of this is that in the 

 ten years and more during which collections of it have been made 

 and observations recorded, it has flourished luxuriantly. But the 

 stand taken in these "inquiries" is that we will not be satisfied 

 merely with what is true "in a general way." 



Questioning further about the creature's adaptation, perhaps 

 the thing we would most like to know is, how did it become fitted 

 to its conditions? A moment's reflection makes it clear that any 

 answers we may get to this question will have to be indirect. — 

 will have to be inferential alone. This is obvious from the fact 

 that such adaptations had already been acquired when the ani- 

 mals first came under observation. The acquirement is, in a 

 word, a matter of the past, consequently irreclaimably beyond 

 the reach of observation. We may indeed conjecture that ac- 

 quirement of adaptation is still in progress, but the prospect of 

 gaining any real satisfaction by pushing study on the basis of 

 such a conjecture is practically nil. since all experience is to the 

 effect that change of organic kinds goes on in nature either ex- 

 ceedingly slowly : or if suddenly, at rare intervals, the sudden- 

 ness and rarity making the chance of witnessing it but slight. 



Undoubtedly experimental work, particularly of recent years, 

 has shown that under conditions that may lie experimentally 

 imposed, new organic kinds may come forth in a very brief time 

 relatively, even though the coming be gradual. Undoubtedly, 

 too, new organic kinds may come forth suddenly by sporting 

 or mutation under natural conditions. But the myriad kinds 

 which, uninterfered with by man. Nature herself presents, if 

 the evidence of paleontology and ages-long observation are to 

 lie trusted, have in the vast majority of cases retained their iden- 

 tity during years and centuries, and even millenniums. And 

 surely it is nature as it is, not as it might he, that science has 

 to interpret. The biologist may sometimes be so carried away 

 or dazzled by the startling results of experiments as to be 

 neglectful of the fact that experiment can have no legitimate 



