98 



Wilson and Cramer 



by Gulewitch, Posner and Gies, Lochhead and Cramer. As a rule, 

 only the phosphorus content was determined in these cases, which is, indeed, 

 a fairly good indicator of the nature of the preparation. It must, however, 

 not be forgotten that preparations have been obtained from brain by Kosse 

 and Freytag, by Noll and by Cramer, which, although having the same 

 phosphorus percentage as protagon, differ in their nitrogen or carbon 

 contents. 



By a method which is described at the end of this paper, we have ex- 

 tracted from brain, by means of boiling absolute alcohol, a substance giving 

 the following analytical results : ^ 



Another sample was prepared by a slight 

 method (see p. 104), and gave on analysis : 



lodification of Gam gee's 



Sample D, 3rd recryst. 



C. 



66-40 



H. 



10-71 



N. 



2-55 



P. 



1-02 



S. 

 0-68 per cent. 



It is this constancy of the chemical composition which has induced many 

 physiological chemists to consider protagon as a definite chemical compound ; 

 and, whether this view is right or not, we must insist that the name 

 protagon cannot be applied to substances of a different chemical composition. 

 As a rule, if a chemist tries to prepare a known substance by a given 

 method and fails to obtain the same substance as previous workers, he is 

 inclined to suspect his technique. Some workers on protagon, however, 

 use that name for any substance that has been prepared according to a 

 known method, irrespective of its chemical composition. If a substance of 

 a composition different from protagon is obtained, this is taken as evidence 

 for " the variability and indefiniteness of the protagon mixture." A recent 

 paper on this subject by Rosenheim and Tebb illustrates very instruc- 

 tively the confusion which has arisen with regard to the use of the name 

 protagon. 



In order to bring forward evidence to support Thudi chum's view that 

 protagon is identical with cerebrote, a substance isolated from ox brains by 

 means of alcohol extraction by Couerbe in 1837, Rosenheim and Tebb 

 have repeated Couerbe's method and have analysed the substance obtained 

 in this way. The analytical figures are given here : 



1 The nitrogen was determined by Dumas' method, the phosphorus by Neumann's 

 method, the sulphur by Carius' method. 



