O GENERAL PRINCIPLES OF ZOOLOGY. 



special Physiology exists only for man and the higher 

 vertebrates ; this, too, for the above-named reasons has 

 been made a special branch of science. Paleontology also 

 has, in addition to its specific zoological tasks, attained im- 

 portance as a scientific aid to Geology, since it furnishes 

 the materials for characterizing and fixing the various geo- 

 logical ages and the earth's history during those ages. 

 When, therefore, at the present day we speak of Zoology, 

 we have principally in mind Morphology and Systemization 

 of living animals with consideration of their general vital 

 phenomena. 



The views here given of the character of Zoology have 

 not been the same in all time. Like every science Zoology 

 has developed gradually; it has varied with each epoch 

 and tendency, according as the systematic or the morpho- 

 logical or the physiological point of view was the prevail- 

 ing one. It will now be interesting to take a hasty glance 

 at the most important phases in the development of 

 Zoology. The reader will bring an increased intelligence 

 to the questions which now dominate zoological inquiry, 

 if he knows how these have arisen historically. 



