440 ' CEREBRIXS.' [BOOK i. 



when Diaconow and Hoppe-Seyler first promulgated this idea, the 

 latter body has been generally considered to be a mixture of cerebrin 

 with lecithin. 



The author, in his criticism of the position which had been taken 

 up by Diaconow and Hoppe-Seyler, tried to shew that those who 

 had manifested great scepticism in Liebreich's protagon had taken for 

 granted the existence of a body whose investigation had been infinitely 

 more incomplete 1 . The justness of the criticism has been thoroughly 

 confirmed by the subsequently published researches of Geoghegan 2 . 



Geoghegan's Instead of boiling pounded brain with caustic baryta, 



modeofpre- as Muller had done, Geoghegan extracted pounded 

 paring cere- ^rain with .cold alcohol and ether, then boiled it in 

 alcohol. The white body which separated on cooling, 

 and which according to Geoghegan is a mixture of cerebrin, cholesterin 

 and lecithin, was treated with ether so as to separate cholesterin, 

 and then boiled with baryta water. The insoluble residue was 

 dissolved in alcohol and crystallized. 



It was analysed with the result of finding that it contained only 

 one-third of the amount of nitrogen which had been found by Miiller ; 

 to it the empirical formula Gj3J$f) m is ascribed. 



f 



Mean of Geoghegan's . Mean of Miiller's 

 analyses of cerebrin. analyses. 



C ................ 6874 68-45 



H ................ 1091 11-20 



N ................ 1-44 4-50 



The author's The author's researches on cerebrin, though far from 



researches on complete, were made immediately prior to the publi- 

 cerebrin. cation of Geoghegan's paper, though they have been 



hitherto unpublished. They have led him to the following conclusions : 



(1) By the action of ether, however prolonged, or of alcohol, a 

 phosphorus-free cerebrin cannot be obtained from protagon ; though 

 by boiling with alcohol for many hours protagon appears to be decom- 

 posed, so that by separating the substance which falls first on cooling 

 and subjecting it again to prolonged treatment with boiling alcohol, a 

 body is obtained which differs somewhat in physical characters from 

 protagon ; if this body be many times subjected to the""" action of 

 boiling alcohol and to the above referred-to process of separation, 

 a substance is obtained containing less phosphorus than protagon 

 and having a different composition. This body, which was certainly 

 not absolutely pure, was analysed witli the following results : 



(1) (2) 



C. in 100 parts 64'44 6*23 

 H. 10-46 10-54 

 N. 3-12 



(2) By the action of caustic baryta on protagon there is obtained 



1 Gamgee and Blankenhorn, Op. cit. Journ. of Phys., p. 121. 



2 Geoghegan, " Ueber die Constitution des Cerebrins." Zeitschrift /. pliys. Chemit, 

 Vol. in. (1879), p. 332. 



