CHAP. X.] THE NERVOUS TISSUES. 433 



1. 0-0678 substance gave 0*0083 Mg 2 P 2 7 = 7'83 # P 2 5 . 



2. 0-0985 0-0123 =7'98J 



3. 01833 0024 Pt = TS5gN. 



The formula of lecithin, C^H^NPO^ demands 8'378 g of P 2 5 and 

 117 1 of N. 



Upon these facts, and these alone, so far as the author is aware, 

 all subsequent writers have based their belief in the presence of 

 lecithin in the brain, adopting the views of Diaconow and Hoppe- 

 JSeyler that protagon is a mixture of lecithin with cerebrin *. 



The Author's ^ * s unquestionably true that the precipitate 



criticism of which separates from an alcoholic solution of brain, 

 the observa- contains, besides protagon, cholesterin, and a body for 

 which we may retain the name of cerebrin, small 

 quantities of bodies soluble in ether which have a 

 much higher percentage of phosphorus than protagon, and which 

 possess the general smeary characters of lecithin. But these bodies 

 are present in very small quantities, and are readily removed by ether 

 washing. Protagon which has been several times recrystallized yields 

 no such body as lecithin to ether, in which liquid it is at ordinary 

 temperatures practically insoluble. 



From his own observations then he would conclude that whilst 

 it is true that the brain yields to alcohol other phosphorized bodies 

 than protagon, the latter is much the most abundant of the phos- 

 phorized products, and by no action of ether can it be split up into 

 lecithin and a non-phosphorized cerebrin, it is possible and indeed 

 probable that amongst the phosphorized principles, lecithin is to be 

 reckoned. No sufficient proof of its identity has however yet been 

 furnished. It is indeed apparent to the author from his own work, 

 no less than from a careful study of the researches of Thudichum, 

 that the phosphorized ingredients are numerous. 



Description of some of the products of decomposition of lecithin 

 and protagon. 



Whichever the view adopted, it appears that certain of the pro- 

 ducts of decomposition of lecithin and protagon are the same. The 

 chief of these are glycerin-phosphoric acid, neurine or choline, and 

 fatty acids; the two former of these bodies will now be described. 



Glycerin-phosphoric acid (C S H 9 P0 6 ). 



When distearyl-lecithin is decomposed by boiling with alkaline 

 solutions, it combines with the elements of water, with the formation 



1 The author has attempted to separate lecithin from brains by Diaconow's method 

 and has failed entirely. 



a. 28 



