6 ZOOLOGY. 



constituting the body of the animal or plant. Between the 

 organs and the functions they perform there is a necessary 

 co-relation; the muscles, for example, are the immediate 

 instruments or organs of motion : while the organs of sense 

 inform us of what surrounds us. 



13. Relations under ivhich Living Beings are Studied. 

 The study of the mode of conformation of the organs of an 

 animal or plant is called anatomy ; the study of their func- 

 tions, physiology. Anatomy is the science of structure ; 

 physiology the science of life. These sciences are mutually 

 dependent, and cannot be studied apart with advantage. A 

 knowledge of mere structure is unimportant, unless combined 

 with a knowledge of function. 



Anatomy and physiology constitute the basis of the natural 

 history of organized beings ; but these must also be studied 

 under other relations. Hence the study of external characters, 

 in order to distinguish animals and plants readily and with 

 certainty from each other. Classification also, to aid the 

 memory, becomes requisite. The distribution also of animals 

 and plants over the globe is a matter of interest, practically 

 and scientifically ; while the laws regulating the distribution 

 merit careful study. The same remark applies to the uses 

 man makes of natural objects. Finally, natural history is 

 not occupied solely with what now exists upon the globe ; but 

 by the examination of fossil remains endeavours to discover 

 the history of those ancient inhabitants of the earth, of which 

 so many existed before man himself. 



These varied studies naturally divide themselves into two 

 branches : the study of plants is called botany ; zoology 

 means the history of the animal kingdom. 



GENERAL CHARACTERS OF.ANIMALS. 



14. Differences between Animals and Plants. In the 

 immense majority of cases, nothing is easier than to dis- 

 tinguish an animal from a plant; yet occasionally this is 

 difficult, in consequence of the great simplicity of structure in 

 some animals. This uncertainty, after all, may belong rather 

 to the imperfection of our knowledge than to the nature of 

 things ; and thus it may be said generally, without dwelling 

 more on this subject, that animals differ from plants by cha- 

 racters of high importance, drawn from the nature of the 

 phenomena connected with their mode of life, from their 



