152 Prof. A. Gamgee and Dr. E. Blankenhorn. [June 19, 



Protagon is soluble with difficulty in cold, but more easily in warm 

 alcohol and ether. At higher temperatures than 55° C, alcohol 

 appears to decompose protagon. In water protagon swells and pre- 

 sents 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, aild a base to which he 

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

 ascribed the formula CrH^lSTClgPt. This base was afterwards shown 

 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 — has come to be universally denied. 



By Diaconow, Hoppe-Seyler, and Thudichum it is denied that any 

 such definite substance exists, and Liebreich's protagon is held to be 

 a mechanical admixture of a phosphorized body termed lecithin, 

 C 44 H 90 NPO 9 , with a nitrogenous, non-phosphorized, body termed cere- 

 brin. 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. 



It is not our intention in this communication to enter into a 

 full criticism of the views of those who have preceded us in the 

 investigation of the existence or non-existence of protagon, and we 

 shall confine ourselves to a statement of a few of the chief objections 

 which appeared to us as insurmountable obstacles in the way of 

 accepting Diaconow's and Hoppe-Seyler's statements. 



Liebreich's protagon was described by its author as a white non- 

 hygroscopic substance, which could, by suitable treatment, be con- 

 stantly obtained in a crystalline form, and this description will be 

 shown in the sequel to be absolutely correct. 



Cerebrin is a body most imperfectly known, obtained by its dis- 

 coverer, Miiller,* by pounding up brains with baryta water to the con- 



* Dr. Wilhelm Mvller. " Ueber die Chemischen Bestandtlieile des Grehirns- 

 zweite Abliandlung." ." Annalen der Chemie und Pharmacie." Bd. cv (1858), 

 s. 361. 



