The Cerebrosides of Brain Tissue. 



93 



The experiment proves the economical use of carbohydrate during 

 periods of work. On the contrary, when 700 grams of meat were 

 given and the dog was compelled to run, the heat production was 

 increased by that quota which would have been added from the 

 specific dynamic action of the protein metabolized. The latter 

 observation confirms Rubner ; the first observation has never been 

 reported. The principles are of importance in the proper arrange- 

 ment of dietaries for those who execute mechanical labor. 



58 (1236) 

 The cerebrosides of brain tissue. 



By P. A. Levene and C. J. West. 



[From the Rockefeller Institute for Medical Research, N. Y.] 



Since the work of Thudichum, evidence has existed that there 

 was more than one cerebroside. On the basis of physical proper- 

 ties and analyses, Thudichum distinguished two cerebrosides, 

 phrenosin and kerasin. He had the correct intuition as to the 

 points of difference of the two cerebrosides, and suggested that 

 this difference was in the nature of one component, namely, the 

 fatty acid. As far as he worked, the other components were 

 identical in all cerebrosides. Unfortunately his method of separa- 

 tion was imperfect. Therefore, each fraction contained a large 

 portion of the other. When the fatty acids were obtained, they 

 analyzed approximately for a stearic acid, which Thudichum 

 named neuro stearic acid. Subsequent workers improved the 

 methods of purification particularly that of phrenosin; this per- 

 mitted the isolation of the fatty acid, cerebronic acid. This acid 

 was identified by Thierf elder as an hydroxy pentacosanic acid, 

 C25H50O3. The further work on cerebrosides brought nothing 

 new as regards their structure. The attempt of Thierfelder to 

 classify them on the basis of their sugar contents was futile. 

 Finally, it was possible to isolate from a cerebroside corresponding 

 to Thudichum's kerasin, a fatty acid of different structure from 

 cerebronic acid, namely, lignoceric acid. This acid was isolated 

 nearly simultaneously in three laboratories, but its relation to 

 cerebronic and lignoceric acids was first established in our labora- 

 tory, and independently of us by Rosenheim. Since then, it has 



