190 PHOSPHORUS SEEMS ESSENTIAL 



nitrogen. The organic constituents of bile resem- 

 ble the acid resins in physical characters, and yet 

 contain nitrogen. The organic alkalies are inter- 

 mediate in their physical characters between the 

 fats and resins, and they all contain nitrogen. A 

 nitrogenised fatty acid is as little improbable as the 

 existence of a nitrogenised resin with the characters 

 of a base. 



97. An accm*ate investigation would probably 

 discover differences in the composition of the brain, 

 spinal marrow, and nerves. According to the ob- 

 servations of Valentin, the quality of the cerebral 

 and nervous substance is very rapidly altered from 

 the period of death, and very uncommon precau- 

 tions would be required for the separation of foreign 

 matters, not properly belonging to the substance of 

 the spinal marrow or brain. But, however difficult 

 it may appear, the investigation seems yet to be 

 practicable. We know, in the meantime, that all 

 experience is against the notion of a large amount 

 of carbon and hydrogen in the substance of the 

 brain. The absence of nitrogen as an element of 

 the cerebral and nervous matter, appears, at all 

 events, improbable. This substance, moreover, can- 

 not be classed with ordinary fats, because we find 

 the cerebric acid combined with soda, whereas, all 

 fats are compounds of fatty acids with oxide of 

 glycerule. In regard to the phosphorus of the 

 brain, we can only guess as to the form in which 

 the phosphorus exists. Walchner observed re- 



