CHAP, v.] NUTRITION. 435 



tion as to the nature of the metabolism is however wanting. The 

 thyroid and thyrnus bodies, often in descriptions associated with the 

 spleen, though different in structure, the former absolutely so, re- 

 semble the spleen somewhat, as far as their extractives are 

 concerned. The thymus contains leucin, xanthin and hypoxanthin, 

 with lactic and succinic acids ; uric acid seems to be absent. The 

 extractives of the thyroid are scanty, but apparently of the same 

 nature. 



28 2 



