ANATOMY AND PHYSIOLOGY 



functions. But so extremely intricate is the chemistry 

 of the substances involved that in no single case has 

 the exact nature of the metabolisms wrought by these 

 organs been fully made out. Each is in its way a 

 chemical laboratory indispensable to the right con- 

 duct of the organism, but the precise nature of its op- 

 erations remains inscrutable. The vast importance of 

 the operations of these intermediate organs is unques- 

 tioned. 



A consideration of the functions of that other set of 

 organs known collectively as the nervous system is 

 reserved for a later chapter. 



