68 (238) Society for Experimental Biology and Medicine. 



stituents of protoplasm and that a study of living matter must 

 include the consideration of these compounds of the fatty acids. 



The phosphorized fats, or lipoids, which have been most care- 

 fully studied have been obtained from the brain, 1 but even as 

 derived from this source, where they are believed to be present in 

 relatively large amounts, their constitution and mutual relationships 

 have not been clearly established. 



During investigations of alcoholic extracts of kidneys, the writer 

 has been led to infer that substances closely related to the lipoids 

 derived from the brain may be obtained by similar methods from 

 the kidney, and the purpose of the present communication is to 

 report a few representative analyses from among those upon which 

 the inference just stated is based. 



Extracts of finely divided renal tissue, freed from obvious fat, 

 made with hot 85 per cent, alcohol, yield a precipitate, upon 

 cooling, which contains a variety of lipoids, while certain others 

 remain in solution. For convenience, those lipoids which- are 

 relatively insoluble in cold alcohol may be classed as the " pro- 

 tagon " group, and those not precipitated on chilling as the 

 " lecithin " group. A preliminary purification of the " protagon " 

 group was effected by treating the crude precipitate with benzol, 

 which left a small residue undissolved. From the concentrated 

 solution in benzol a powdery precipitate was formed upon the 

 addition of a mixture of acetone and rhigolene and became pure 

 white when repeatedly washed with the latter mixture, in which it 

 was nearly if not wholly insoluble. This precipitate was soluble 

 in hot 85 per cent, alcohol, from which it separated in discoid 

 crystals on cooling the solution. It corresponded in solubilities to 

 Liebreich's " protagon " or to an impure sphingomyelin described 

 by Thudichum, and obtained from the brain. It contained 2.869 

 per cent, of phosphorus and 3.126 per cent, of nitrogen. A por- 

 tion of this precipitate was dissolved in hot 85 per cent, alcohol 

 and an alcoholic solution of lead acetate was added to excess. The 

 mixture was boiled and filtered while hot. Upon cooling, a heavy 

 white crystalline precipitate formed. This was removed by filtra- 

 tion and recrystallized from 85 per cent, alcohol four times. The 



1 Thudichum : Die Chemische Konstitution des Gehirns des Menschen und der 

 Tiere. Tubingen, 1901. 



