On Protagon 



99 



Although the composition of Couerbe's cerebrote differs markedly from 

 Rosenheim and T ebb's substances, they call their substances Couerbe's 

 cerebrote, because they have obtained these substances by using Couerbe's 

 method. A comparison of these figures with the analyses of protagon given 

 above shows that not one of these " cerebrotes " has the same composition 

 as protagon. Nevertheless Rosenheim and Tebb conclude that protagon 

 and cerebrote — it is not said which of the three cerebrotes — are the same 

 substance under two different names, because the same solvent has been 

 used for their preparation and because there is some superficial resemblance. 



It seems almost unnecessary to demand that investigations on protagon 

 intended to demonstrate the composite nature of this substance should be 

 made on material the identity of which with protagon is beyond doubt. 

 But a critical survey of these observations will show that even here the 

 same tendency to identify protagon by its method of preparation, against 

 the evidence of the analytical results, is apparent, although not in such an 

 exaggerated form as in the case just discussed. 



The substance which Worner and Thierfelder called protagon, and 

 from which they isolated cerebron, was prepared according to Gam gee's 

 method. The analytical results of the carbon, hydrogen, and nitrogen 

 determinations show variations from 62-37 per cent. C. to 68-97 per cent. C, 

 and from 2-39 per cent. N. to 3-39 per cent. N. The phosphorus was not 

 determined. 



Posner and Gies have obtained substances by means of Gam gee's 

 method with a phosphorus percentage varying from 1-73 to 0-89. All 

 their products they call indiscriminately "protagon." This is the more 

 remarkable since Gies in his first investigations on this subject had worked 

 with substances which had the same chemical composition as protagon, 

 and since Posner and Gies themselves had obtained substances the 

 phosphorus percentage of which was identical with that of protagon. 

 Although these observers had the personal experience that a substance 

 of the definite composition of protagon can be obtained, tliey do not 

 hesitate to apply this name also to a substance of a difterent composition. 



Rosenheim and Tebb even go so far as to apply the name protagon 

 to substances which show an entirely opposite behaviour towards a certain 

 solvent. On page 6 these authors state that acetone is a suitable solvent 

 for protagon. On the next page they give the results of subjecting a sample 

 of protagon twice recrystallised to fractional crystallisation from acetone. 



