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 inor- 

 ganic world, whilst the second is occupied with the investi- 

 gation of the nature and relations of all bodies which exhibit 

 life. The former department concerns the geologist and mi- 

 neralogist, and secondarily the naturalist proper as well ; the 

 latter department, treating as it does of living beings, is pro- 

 perly designated by the term Biology (from /3/oc, life, and 

 Xo'yos, 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 the 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 (Foraminifera) cannot be said to 



VOL. I. A 



