June 22, 1900.] 



SCmNGE. 



967 



The year 1859 found zoologists, the 

 world over, working industriously and 

 quietly at almost purely descriptive work. 

 No more was expected of any zoologist than 

 that he should discover and record the 

 wonders of nature as revealed in the animal 

 kingdom, and that he should duly express 

 his astonishment at the infinite wisdom 

 shown by the creator in arranging all these 

 details. Of attempts to get at the meaning 

 of the details there were very few. The 

 popular notion of the zoologist's aim in life 

 is expressed in a question that I remember 

 to have heard asked in my student days, by 

 a much respected professor of literature of 

 his zoological colleague. " Well now what 

 is that animal curious for ?" In this year 

 appeared Darwin's ' Origin of Species. ' Its 

 effect is thus graphically described by V. 

 Graff in a recent lecture. " It came like a 

 lightning flash in a period of quiet descrip- 

 tive work, a period which had accustomed 

 itself to consider the nature-philosophy ideas 

 of the beginning of the century as absurd 

 freaks of imagination, unproved and un- 

 provable, a period which therefore clung 

 anxiously to its foundation of facts. How 

 the theory of natural selection put life into 

 this dry describing, how it hurried the knife 

 of the anatomist, and what a broad prospect 

 it opened before the hitherto short sighted 

 eye of the systematist ! About the mum- 

 mies of the species which, separated from 

 one another by carefully formulated Latin 

 diagnoses, filled the collections, there sud- 

 denly appeared the constricting noose of 

 blood relationship. The petrified remains 

 of extinct forms, hitherto shut out from the 

 community of living beings, received flesh 

 and blood and demanded to be included 

 with the existing fauna and flora in a single 

 great genealogical tree, representing the 

 history of life on our earth." 



Darwin's book brought essentially two 

 contributions. In the first place it brought 

 a mass of evidence in proof of the proposition 



that animals are related to one another by 

 descent. The idea of a process of evolution 

 is very old and Osborn has recently traced 

 its history from the early Greeks to the 

 time of Darwin. Darwin did not originate 

 the idea, he established it by a mass of evi- 

 dence and it has been ever since accepted. 



In the second place Darwin contributed 

 the theory of the origin of species by natural 

 selection. This theory is so well known 

 that it need not be restated here, but it may 

 perhaps be pointed out that the theory does 

 not attempt to account for the origin of the 

 variations upon which it depends. It is a 

 fact that these variations occur and Dar- 

 win's theory bases itself upon this fact. He 

 spoke of such variations as fortuitous. 

 Aside from certain correlations, variations 

 seemed to Darwin to occur by chance, though 

 he did not exclude the possibility of their 

 being later found to be subject to law. 



The idea that the multitude of animal 

 forms had thus originated by a process of 

 evolution, and that this process was gov- 

 erned by a simple law, affected the whole 

 subsequent course of zoology. 



Zoologists soon came to accept not only 

 evolution as a process, but natural selection 

 as at least the chief explanation of the proc- 

 ess. The zoologists following Darwin made 

 but little attempt to study the variations 

 upon which the theory of natural selection 

 based itself, or to determine the range of 

 variations or their causes . Having decided 

 that animals were related to one another, 

 and having fixed the law governing the 

 origin of the relationship, zoologists began 

 to turn their attention to a study of the 

 degree of relationship. A mania seems to 

 have become prevalent for the construction 

 of a genealogical tree of the entire animal 

 kingdom. The ultimate aim of zoologists 

 ten years ago, or even five years ago was 

 animal genealogy, and such is still the aim 

 of many working zoologists. Paleontology, 

 comparative anatomy and embryology were 



