On Protagon 105 



was extracted for four hours with alcohol and three times recrystallised, 

 the solution being effected in each case by warm alcohol in three-quarters 

 of an hour. The products which Posner and Gies obtained by this method, 

 and which had such an abnormally high phosphorus constant, were prepared 

 by extractions lasting for twenty-four hours. In purifying the crude 

 product by recrystallisation it was treated with alcohol for periods varying 

 from five to fifteen hours. 



In order to test the validity of our conclusion that it is the prolonged 

 treatment with warm alcohol which is responsible for the failure to obtain 

 protagon, we have applied Gamgee's method in the same way as before, only 

 extending the extraction to twenty-four hours, and the treatment with 

 warm alcohol for the solution of the crude product in the recrystallisation 

 process to twelve hours. The specific rotatory power of the substance 

 which had been prepared in this way was [ajn — 13"12, refr. index 1"5039. 

 This substance was, therefore, not protagon, whatever the results of the 

 chemical analysis would have been. 



We can also understand the apparently paradoxical fact that a protagon 

 sample, obtained after repeated crystallisation and identical in every respect 

 with protagon, may appear after a further recrystallisation to be con- 

 taminated with pseudocerebrin or other substances. Formerly pseudocerebrin 

 was held to be extracted from brain, together with protagon, from which it 

 had to be separated. We know now that this substance (which is identical 

 with cerebrin) is formed from protagon by the hydrolysing action of warm 

 alcohol. If, therefore, in the process of recrystallisation the alcohol has been 

 allowed to be in contact with protagon for a longer time than in the 

 previous recrystallisation — and as the destructive action of warm alcohol 

 has not been suspected previously, such a condition may have easily 

 occurred — decomposition products will be formed, and after this recrystal- 

 lisation the protagon may really be less pure than it was before. 



Method for the Preparation of Protagon. 



In order to shorten as much as possible the time during which the hot 

 or warm solvent is in contact with the material in the preparation of 

 protagon, we have adopted the following procedure, which we have found 

 to be a most convenient method for the prepai'ation of protagon. 



The brain mass is made into a pulp and treated repeatedly with 96 per 

 cent, alcohol in a wide-mouthed bottle. The extraction is accelerated by the 

 use of a shaking machine, the material being kept afterwards in an ice chest. 

 After three to four extractions ether is added instead of alcohol, and the 

 treatment continued until lecitliin and cholesterin are completely extracted. 

 After removing the ether by filtration and drying the remaining mass by 

 exposing it to the air at room temperature, a brown mass remains which 

 can be made easily into a fine powder. To this powder any solvent can be 

 applied directly. We have prepared protagon from it according to 



