590.9 3^4 



II. 



Zoolo^ since Darwin.' 



Part III. 



NOW that we have seen what new paths zoology has taken since 

 the time of Darwin, let us consider how its old, once exclusive, 

 tasks, the description of the present state of animal forms, and the 

 observation of their vital activities, have grown into systematics and 

 biology in the narrower sense. 



The theory of natural selection gave a new and mighty impulse 

 to biology after it had been for a long time neglected. It entered on 

 a flourishing period, which can only be compared to the brilliant age 

 of biological discoveries made by Reaumur, Roesel, De Geer, Bonnet, 

 Schaffer, and others in the eighteenth, century. After Darwin's time 

 how important became the relations of animals among themselves 

 and to the plants, the influence of climate and food, and of 

 light and warmth in the struggle for existence, in the phenomena of 

 natural selection ! The whole world afforded material, and books 

 appeared, like H. W. Bates' " The Naturalist on the Amazon River," 

 and A. R. Wallace's " The Malay Archipelago," real models of 

 biological study. To these were added a whole host of naturalists, 

 chiefly English and German, who everywhere found in the biology of 

 animals and plants fresh proofs to support the Darwinian theory, 

 though, at the same time, they pointed out puzzHng phenomena, the 

 solution of which, even to-day, defies the intelligence of the naturalist. 

 Yet in this, as in other subjects, we know very well that neither our 

 knowledge, nor our efforts, nor our means of arriving at the truth are 

 as yet complete. 



Formerly, geographical distribution was always reckoned among 

 biological facts. This was probably only due to the fact that at that 

 time people usually sought to explain the problem of the cause of 

 faunistic diff"erences by a reference to life-conditions, and as this 

 seldom was satisfactory, animal geography was in reality a collection 



1 Lecture delivered by Professor Ludwig von Graff on his installation as Rector 

 Magnificus of the K. K. Karl Franzens University in Graz, November 4, 1895. 

 The profits from the sale of the original go to the Freitisch-Stiftung of the 

 University. {Continued from p. 315.) 



