CHAP. I.] 



INTRODUCTORY. 



13 



animal's body is made up^by water, of which it is, therefore, very 

 largely composed, the brain containing about seventy per cent of 

 that fluid. 



In saying that the body consists of different parts and substances, 

 and is made up of combinations of elements, all that is meant is 

 that it can be more or less readily divided into such parts, and that 

 it can be dissolved into such elements, just as water may be destroyed 

 to give place to oxygen and hydrogen. Whilst living, however, 

 the body really forms one continuous whole locally differentiated, that 

 is, assuming different appearances and possessing different properties 

 in different regions. Even the very blood is directly continuous 

 with the other constituents of the body in all actively growing parts. 



