ARISTOTELIAN PERIOD. TT 



of the subordinate subjects of the morphology (or 

 anatomy), physiology, embryology, geographical distri- 

 bution, palaeontology, classification, and evolution of 

 animals. 



Speaking generally, the progress of natural history, as 

 a science, has corresponded precisely with the extent 

 to which these separate departments have had their 

 existence recognised, their boundaries defined, and their 

 inter-relations explored. In the early days of natural 

 history these subdivisions had only a very partial 

 existence, or did not exist at all;- and it was for the 

 most part considered enough to acquire a knowledge 

 of the external characters of animals, and of their habits 

 and mode of life, and to give them names by which they 

 could be arranged in some sort of an order. Not only was 

 this the case, but zoology, properly so called, was for 

 long very imperfectly separated from the sciences of 

 botany, geology, and mineralogy, all of which were 

 regarded as forming parts of the general subject of 

 natural history. 



This imperfect differentiation of the science of natural 

 history may be said to have prevailed generally up to the 

 middle or nearly the end of the eighteenth century. It is 

 therefore all the more surprising to find that Aristotle, 

 living in the fourth century before our era, and having 

 little or no previously accumulated knowledge to fall back 

 upon, should have been able to form any philosophical 

 conception of the laws of animal life, or to produce a 

 work which should be thought worthy of profound and 

 minute study by the naturalists of the present day. 



Aristotle's principal work on natural history, namely his 



