THE NERVOUS SYSTEM. 463 



oxalic acid, which is frequently deposited in combination 

 Fig. 131.* Fifj. 132.1 



with lime (fig. 131) as an urinary sediment. Like cystin, 

 but much more commonly, it is the chief constituent of 

 certain calculi. 



A small quantity of gas is naturally present in the urine 

 in a state of solution. It consists chiefly of carbonic acid 

 and nitrogen. 



CHAPTER XVI. 



THE NERVOUS SYSTEM. 



THE nervous system consists of two portions or systems, 

 the cerebro-spinal and the sympathetic or ganylionic, each of 

 which (though they have many things in common) pos- 

 sesses certain peculiarities in structure, mode of action, and 

 range of influence. 



The cerebro-spinal system includes the brain and spinal 

 cord, with the nerves proceeding from them, and the several 

 ganglia seated upon these nerves, or forming part of the 



* Fig. 131. Crystals of oxalate of lime, 

 t Fig. 132. Crystals of cystin. 



