368 THE HISTORY AND SCOPE OF ZOOLOGY IX 



tion (1798) exercised the most important influence on 

 Darwin's tliouglit, as he -himself tells us, and led him 

 to give attention to the facts of animal population, 

 and so to discover the great moving cause of natural 

 selection — the struggle for existence. Darwin may 

 be said to have founded the science of bionomics, and 

 at the same time to have given new stimulus and new 

 direction to Morphography, Physiology, and Plas- 

 mology, by uniting them as contributories to one 

 common biological doctrine — the doctrine of organic 

 evolution — itself but a part of the wider doctrine of 

 universal evolution based on the laws of physics and 

 chemistry. 



The full influence of Darwin's work upon the 

 progress and direction of zoological study has not yet 

 been seen. The immediate result has been, as pointed 

 out above, a reconstruction of the classification of 

 animals upon a genealogical basis, and an investiga- 

 tion of the individual development of animals in rela- 

 tion to the steps of their gradual building up by cell- 

 division, with a view to obtaining evidence of their 

 genetic relationships. On the other hand, the studies 

 which occupied Darwin himself so largely subsequently 

 to the publication of the Origin of Sjjecies, viz. the 

 explanation of animal (and vegetable) mechanism, 

 colouring, habits etc., as advantageous to the species 

 or to its ancestors — in fact, the new Teleology, — has 

 not yet been so vigorously pursued as it must be 

 hereafter. The most important work in this direction 

 has been done by Fritz Miiller (Fu7^ Darwin)^ by 

 Herman Miiller (Fertilisation of Plants hy Insects), 



