of isolated oceanic islands, like the Galapagos and Azores 

 and the clusters of Polynesia, are inhabited by lizards and 

 birds and insects which resemble most closely the species 

 of the nearest bodies of land. Such resemblances are most 

 reasonably interpreted as indicating that the original pro- 

 genitors of the island colonies were stragglers from the 

 nearest mainland, whose descendants have undergone di- 

 vergent evolution during succeeding generations. 



Having, then, this vast store of fact and principle 

 amassed through centuries by countless students, the zool- 

 ogist is entitled to speak positively when he finds a law like 

 the doctrine of evolution that reviews and summarizes the 

 whole range of animal structure. The well-established 

 facts of zoology are the reasons why he asserts with a de- 

 cision often mistaken for dogmatism that evolution is a 

 real process. The further question, why is nature so con- 

 stituted that evolution is true, is an enquiry that does not 

 fall within the limits of zoological science. 



We now come to the second great division of zoology, 

 which as a whole is concerned with broad and deep enquiry 

 into the workings of nature ; it is natural history in the best 

 sense. Prior to the time of Darwin attempts to solve the 

 kinetic problems of the organic world were hampered by 

 anthropomorphism and narrowness of view, as well as by 

 paucity of facts. But since then, owing to the immense 

 influence of the works of that great naturalist, so much at- 

 tention has been given to the fundamental problems of 

 life that it is now possible to correlate many principles 

 which describe not only the fact of evolution but many of 

 the factors as well. And in this modern development wide 

 observation has led so directly to extensive experiment that 

 we may justly characterize the present period as an age of 

 experimental zoology. Just as all the apparently discon- 

 nected studies of structural zoology deal with one mat- 

 ter, evolution, so in the sphere of experimental zoology 



15 



