JANUAEY 1, 1915] 



SCIENCE 



tlie indelible impress of its past ; the extinct 

 animal can be comprehended only in the 

 light of the present. For instance, the 

 paleontologist is most directly concerned 

 with problems 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 car- 

 ried out by experimental studies on exist- 

 ing 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 con- 

 cerning the conditions under which this 

 movement first began to take definite shape 

 as the nineteenth century drew towards 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 

 morphological-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 piti- 

 lessly torn down to give place to new, but to the 

 continuous evolution of zoologie types which de- 

 velop ceaselessly and end by becoming unrecog- 

 nizable to the common sight, but where an expert 

 eye finds always traces of the prior work 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 strug- 

 gle 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 — some- 

 thing, one may suspect, that has played an 

 important part at the higher levels of sci- 

 entific achievement. 



I seem to have been caught unawares in 

 the act of moralizing. If so, let it char- 

 itably be set down as an attempt to soften 

 the hard fact that thirty years after the 

 "Origin of Species" we found ourselves 

 growing discontented with the existing 

 methods and results of phylogenetic inquiry 

 and with current explanations of evolution 

 and adaptation. Almost as if by a pre- 

 concerted plan, naturalists began to turn 

 aside from historical problems in order to 

 learn more of organisms as they now are. 

 They began to ask themselves whether they 

 had not been over-emphasizing the prob- 

 lems of evolution at the cost of those pre- 

 sented by life-processes everywhere be- 

 fore our eyes to-day. They awoke to 

 the insufficiency of their traditional meth- 

 ods of observation and comparison and they 

 turned more and more to the method by 

 which all the great conquests of physico- 

 chemical science had been achieved, that 

 which undertakes the analysis of phenom- 



