28 INTRODUCTION, 



animal characters, is founded on the difference of 

 relations above insisted on. 



Of the forms peculiar to the organic elements of the Ani- 

 mal Body, and cf the principal combinations of chemical 

 elements. 



A porous texture and three chemical elements * 

 are essential to the composition of every living body; 

 to that of the animal body a fourth '[ element is pe- 

 culiarly requisite. This porous texture is composed, 

 as it were, of meshes of a variety of forms, and these 

 elements are united together in different combina- 

 tions. There are three descriptions of organic ma- 

 terials or forms of texture, the cellular membrane, 

 the muscular fibre, and the medullary substance, to 

 each of which is attached a peculiar combination of 

 the chemical element?, as well as an appropriate 

 function. 



The cellular membrane consists of an assemblage 

 of fibres and lamina; of animal matter so mutually 

 connected as to form a number of small cells, or ca-^ 

 vities. It pervades every part of the animal struc- 

 ture, and may be considered as a kind of sponge 

 similar in form to the entire body, possessing a pro- 

 perty of contraction to an indefinite degree, when 

 the causes which preserve it in a state of tension 

 are removed. It is this power which retains the 



* Oxygen, hydrogen, and carbon, 

 t Azote. 



