FUNCTIONS OF ANIMALS. 9 



and dried up, so as to form lamellae, as may be seen on the 

 surface of the skin. 



Anatomists describe other tissues as entering into the com- 

 position of animal bodies, such as the serous and mucous 

 membranes, the different varieties of the fibrous tissues, the 

 cartilages, the osseous tissue, &c. ; but, according to all ap- 

 pearance, these varied tissues are only modifications of the 

 utricular or connective. 



20. These tissues, differently combined, and affecting a 

 variety of forms, constitute the different organs by which the 

 faculties of animals are exercised. The term apparatus is 

 applied to an assemblage of these organs, and that of function 

 to the action of a single organ or of many. The apparatus of 

 locomotion, for example, means the assemblage of organs, 

 whatever they be, required for fas function of locomotion or 

 motion from place to place. The structure of animals varies, 

 then, with their faculties and mode of life ; and generally it 

 may be said, that the more vaiied the functions are in any 

 animal the more complex will be its structure. 



CLASSIFICATION OF THE FUNCTIONS OF ANIMALS. 



21. The functions of animals have a relation to two 

 objects, namely, 1. The conservation or preservation of the 

 individual ; 2. The conservation of the race. Of the former, 

 some have reference chiefly to the support and nourishment 

 of the body ; others place the individual in relation to sur- 

 rounding objects. Hence the division of the functions into 

 three great classes, those of nutrition, relation, and repro- 

 duction. The first and last of these collectively have been 

 called vegetative life : the functions of relation, physiologists 

 are agreed to call animal life, as being peculiarly the attri- 

 butes of animals] nutrition and reproduction are functions 

 which animals have in common with plants. 



Each of these great physiological divisions is subdivided in 

 its turn into several others, all tending towards one end ; 

 thus, the nutrition of an animal is accomplished only by the 

 aid of several functions, such as digestion, circulation, respi- 

 ration, &c. : digestion, in its turn, resolves itself into masti- 

 cation, insalivation, deglutition, the transformation of the 

 food into chyme, the extraction of the chyle contained in 

 the chyme, the absorption of this chyle, and the expulsion 

 from the body of the residue of the aliment; finally, these 



