49 



hand, or such as are to be thrown off immediately 

 are all acid, for instance, sweat, urine, milk, and 

 the free acid which they contain is lactic. 



What I have hitherto remarked, constitutes 

 the sum of our knowledge relative to the two 

 systems, on which animal life principally de- 

 pends, viz. the nerves and blood vessels. Through 

 these, the other branches of the body execute the 

 various operations, for which they are destined. 

 They consequently escape our notice as to thd 

 manner in which they perform their functions ; 

 our examinations are therefore limited to what 

 they perform. 



The internal parts of the body lie closely joined 

 to each other, leaving only small interstices, filled 

 with a peculiar matter, which, from its struc- 

 ture has obtained the name of cellular texture. 

 To form to ourselves some idea of this matter, 

 we may consider it as an intervening medium, 

 intended to prevent any one space from being 

 empty. This cellular texture consequently ex- 

 tends itself over the whole body, and is met with 

 in all its parts, connecting itself with the interior 

 parts of several of them, as for instance, with the 

 muscles. Its composition has been but imper* 



E 



