THE PHYSIOLOGICAL CHEMISTRY OF NERVES. 533 



the medulla, and not in a free isolated state." . . . "Besides 

 cholesterin, 'white 7 nervous matter contains a less, but still 

 considerable, quantity of complex fat whose nature is disputed. 

 According to some authorities rather less than half this com- 

 plex fat consists of a peculiar body, lecithin, which we have 

 already seen to be present also in blood-corpuscles and in mus- 

 cle. Lecithin contains the radical of stearic acid (or of oleic, 

 or of palmitic acid), associated, not as in ordinary fats with 

 simple glycerin, but with the more complex glycerin-phosphoric 

 acid, and further combined with a nitrogenous body, neurin, 

 an ammonia compound of some considerable complexity; it is 

 therefore of remarkable nature, since, though a fat, it con- 

 tains both nitrogen and phosphorus." Cholesterin (C 26 H 44 0), 

 lecithin (C 44 H 90 NP0 9 ), and neurin (C 5 H 15 ]ST0 2 ), as shown by 

 the formulae, are all oxygen-containing bodies. May this sup- 

 posed coating and insolating material, myelin, not be to the 

 nerve what myosinogen is to muscle? 



Cholesterin, we have seen, is associated with hepatic func- 

 tions. "It is singular," says Professor Foster, "that, besides 

 being present in such large quantities in nervous tissue, and 

 to a small extent in other tissues and in blood, cholesterin is 

 a normal constituent of bile." We have previously referred to 

 the fact that this alcohol, the only one which occurs in the 

 body in a free state, combines with glycocholic acid in the 

 formation of bile, and is thus eliminated by the liver. This 

 view sustains that of Austin Flint, who looked upon cholesterin 

 as an excrementitious product derived from the nervous sys- 

 tem: i.e., the result of nerve-metabolism. Cholesterin is pres- 

 ent in abundance in the white substance of the cerebro-spinal 

 axis, as well as in the myelin, or white substance of Schwann, 

 in nerves. We have seen, however, that the elimination of 

 excrementitious products by the liver is carried out by the 

 combination of various agencies: mainly glycocholic and tauro- 

 cholic acids derived from cholic acid through an oxidation 

 process in which the oxidizing substance plays the predomi- 

 nating role. That an oxidation process also occurs in a nerve 

 during functional activity is suggested by the following lines 

 of Mathias Duval: "Direct experimentation has shown that the 

 functionating nerve is the seat of increased combustion; this 



