ZOOLOGY 443 



demonstrates the evolution of species as a universal process, while the 

 broad study of the dynamic relations of animals is concerned with the 

 causes of this process, as what we may venture to call the physiology 

 of evolution. In brief, then, the great questions of zoology are the 

 what and the how of evolution. 



In view of the earlier lectures, it is unnecessary to speak at length 

 of classification or taxonomy — the first division of static or structural 

 zoology. Aristotle, who gathered and studied some five hundred of 

 the more common animals of the earth and shore and sea, and the 

 medievalists, Wotton and Eay, Gesner and Aldrovandi, were animated 

 primarily by the instincts of the collector of interesting information. 

 Linnaeus, the great figure of the eighteenth century, rendered an 

 immortal service to zoology (and botany, too) by introducing the 

 present ordered system of naming and classifying organisms. But 

 classification was to Linnaeus an end in itself, he could not see that 

 it was but a means to the larger end of understanding and expressing 

 evolutionary relationships — that resemblance meant consanguinity. It 

 remained for Erasmus Darwin, the elder St. Hiliare, Lamarck and 

 others to appreciate this inner meaning which so vivifies the otherwise 

 dead details of taxonomy. 



The many connected details of animal structure and development 

 and function constitute the threads, as it were, which are interwoven 

 by comparative treatment to form the warp and woof of the fabric of 

 zoology. Classification draws upon this fabric the pattern of genealog- 

 ical connections, emphasizing those threads that run furthest, the 

 so-called distinctive or diagnostic characters. And though the pattern 

 must be altered here and there as knowledge increases, the zoologist 

 feels that it has a real significance as a representation of evolutionary 

 descent. 



As more and more of the lower animals were brought by the micro- 

 scope from the obscurity of their zoological underworld, as exploration 

 revealed more of the creatures of previously unknown lands, as inves- 

 tigation became more detailed and intensive, comparative anatomy 

 arose as an independent branch of zoology with distinct purposes of 

 its own; and it gained its specific form and character from the studies 

 of the great zoologists of the early nineteenth century — Lamarck, 

 Cuvier, Geoffroy St. Hiliare, Goethe, Owen and Oken. These natur- 

 alists dissected and compared the various organic systems of animals, 

 following them as widely as possible from group to group of the 

 numerous vertebrate and invertebrate forms, and they and their fol- 

 lowers have placed the doctrine of evolution upon the sure and broad 

 foundation of comparative anatomy. The main principle of this 

 department of zoology is that the varied forms of animals exhibit 

 deep-seated likenesses that place them in groups related to one another 



