426 PROTAGOX. [BOOK i. 



solution. The substance thus obtained could be recrystallized re- 

 peatedly. As a result of his analyses Liebreich ascribed to protagon 

 the formula C^H^N.OJP. 



Properties Protagon is soluble with difficulty in cold, but more 



of Protagon, easily in warm alcohol and ether. At higher tempera- 

 according to tures than 55 C., alcohol appears to decompose protagon. 

 In water protagon swells and presents the appearance of 

 an opaque jelly, ultimately dissolving so as to form an opaque 

 solution. Liebreich found that protagon was soluble in glacial acetic 

 acid, which deposited it again in a crystalline form, when subjected to 

 the action of cold. 



When boiled with a solution of barium hydrate protagon is 

 decomposed, yielding glycerin-phosphoric acid, fatty acids of which 

 he isolated stearic acid in a state of purity, and a base to which he 

 gave the name of neurine, and to the platinum compound of which he 

 ascribed the formula C 5 H 14 NCl 3 Pt. This base was afterwards shewn 

 to be identical with the base which Strecker had separated from bile 

 and termed choline. 



Although the absolute accuracy of a large number of Liebreich's 

 facts has been placed beyond question, the cardinal fact itself that 

 protagon is a definite phosphorized principle contained in nervous 

 matter had, until lately, come to be universally denied. 



Hypothesis -By Diaconow, Hoppe-Seyler, and Thudichum it is 



that protagon denied that any such definite substance exists, and 

 is a mixture Liebreich's protagon is held to be a mechanical admix- 

 ture of a ph s P norized bod J termed lecithin, CJHJNPO,, 

 with a nitrogenous, non-phosphorized, body termed 

 cerebrin. The presence of phosphorus in protagon is said to be due 

 to contamination with lecithin, and in support of this view it is 

 alleged that by extracting protagon with ether, the substance loses more 

 and more phosphorus. According to Diaconow and Hoppe-Seyler's 

 admission, the phosphorus does adhere most obstinately and cannot be 

 entirely got rid of, though Dr Thudichum thinks he has, by mere 

 extraction with ether, obtained cerebrin (or cerebrines) quite free from 

 phosphorus. 



According to Diaconow 1 by repeated extractions with ether, the P 

 contained in protagon may be made to sink to 1 per cent., whereas, 

 according to Liebreich's formula, it should contain 1*5 per cent. 

 Actually, in the three determinations which he made, Liebreich 

 obtained 11, I'l, and 1*5, as the amount of phosphorus in 100 parts, 

 but, unfortunately, he seems to have concluded that the highest number 

 was correct and made it the basis of his calculation. 



In the year 1877, the Author, assisted by Mr Leopold Larmuth, 

 Platt Physiological Scholar, commenced in the Physiological Labora- 



1 Diaconow, "Das Lecithin im Gehirn." Centralblatt filr die medicin. Wissen- 

 schaften (8 Februar 1868). Nr. 7, Pag. 97. 



