MANUAL OF ZOOLOGY. 



GENERAL INTRODUCTION. 



I. Definition of Biology and Zoology. 



Natural History, strictly speaking, and as the term itself 

 implies, should be employed to designate the study of all 

 natural objects indiscriminately, whether these are organic 

 or inorganic, endowed with life, or exhibiting none of those 

 incessant vicissitudes which collectively constitute vitality. 

 So enormous, however, have been the conquests of science 

 within the last century, that Natural History, using the term 

 in its old sense, has of necessity been divided into several 

 more or less nearly related branches. 



In the first place, the study of natural objects admits of 

 an obvious separation into two primary sections, of which the 

 first deals with the phenomena presented by the inorganic 

 world, whilst the second is occupied with the investigation of 

 the nature and relations of all bodies which exhibit life. The 

 former department concerns the geologist and mineralogist, 

 and secondarily the naturalist proper as well ; the latter de- 

 partment, treating as it does of living beings, is properly 

 designated by the terra Biology (from Bki, life, and ^-iiyoi, a 

 discourse). Biology, in turn, may be split up into the sciences 

 of Botany and Zoology, the former dealing with plants, the 

 latter with animals; and it is really Zoology alone which is 

 nowadays understood by the term Natural History. 



In determining, therefore, the limits and scope of Biology, 

 we are brought at the very threshold of our inquiry to the 

 question, What are the differences between dead and living 

 bodies ? or rather, in the first place, what are the characteris- 

 tics of an organised as compared with an unorganised body ? * 



• The differences between dead or inorganic bodies on the one hand, 

 and living or organic bodies on tlie other, may be taken for all practical 

 purposes as the same as those between unorganised and organised bodies. 

 It is quite true that certain living beings {Foramini/era) cannot be said to 



