PROGRESS IN ZOOLOGY — WILSON. 397 



be? We often find it convenient to lay the emphasis on one or the 

 other of these questions, but fundamentally they are inseparable. 

 The existing animal bears the indelible impress of its past; the ex- 

 tinct animal can be comprehended only in the light of the present. 

 For instance, the paleontologist is most directly concerned with prob- 

 lems of the past, but at every step he is confronted by phenomena 

 only to be comprehended through the study of organisms as they 

 now are. Our main causal analysis of evolution must be carried out 

 by experimental studies on existing forms. All this seems self- 

 evident, yet the singular fact is that only in more recent years have 

 students of evolution taken its truth fully to heart. And here lies 

 the key to the modern movement in zoology of which I propose to 

 speak. 



I do not wish to dwell on matters of ancient history, but permit 

 me a word concerning the conditions under which this movement 

 first began to take definite shape as the nineteenth century drew to- 

 ward its close. In the first three decades after the " Origin of 

 Species" studies upon existing animals were largely dominated by 

 efforts to reconstruct their history in the past. Many of us will 

 recall with what ardor naturalists of the time threw themselves into 

 this profoundly interesting task. Many of us afterwards turned to 

 work of widely different type ; but have our later interests, I wonder, 

 been keener or more spontaneous than those awakened by the mor- 

 phological-historical problems, some of them already half forgotten, 

 which we then so eagerly tried to follow ? I am disposed to doubt it. 

 The enthusiasm of youth? No doubt; but something more, too. 

 Efforts to solve those problems have in the past often failed; they 

 no longer occupy a place of dominating importance; but they will 

 continue so long as biology endures, because they are the offspring 

 of an ineradicable historical instinct, and their achievement stands 

 secure in the great body of solid fact which they have built into the 

 framework of our science. Says Poincare : 



The advance of science is not comparable to the changes of a city, where old 

 edifices are pitilessly torn down to give place to new, but to the continuous evo- 

 lution of zoologic types which develop ceaselessly and end by becoming unrecog- 

 nizable to the common sight, but where an expert eye finds always traces of the 

 prior worli of the centuries past. One must not think, then, that the old- 

 fashioned theories have been sterile and vain. 



And, after all, science impresses us by something more than the 

 cold light of her latest facts and formulas. The drama of progress, 

 whether displayed in the evolution of living things or in man's age- 

 long struggle to comprehend the world of which he is a product, 

 stirs the imagination by a warmer appeal. Without it we should miss 

 something that we fain would keep — something, one may suspect, 



