igis] Casimir Funk 315 



did not diminish the curative power; and no toxic effect was db- 

 served from the administration of the autolytic products, even in 

 ten times the curative dose. 



During the past year I have continued the investigation of yeast, 

 the chief aim having been the improvement of available methods. 

 After many more or less unsuccessful attempts to isolate pure Vitam- 

 ine from such a complicated mixture as that in the alcoholic ex- 

 tract of yeast, it seemed desirable to devise a method that would 

 separate the bulk of the impurities in one Operation, at a stage where 

 the Vitamine is present in stable combination, and would also avoid 

 the use of alkali, which destroys most of the vitamine. The experi- 

 ments were conducted on the alcoholic extract of yeast and on auto- 

 lyzed yeast. 



"Alcoholic extracts." On treating, with acetone, the phospho- 

 tungstate precipitate from alcoholic extract of yeast, about 10 per- 

 cent of the total precipitate remained insoluble. The soluble frac- 

 tion, which formed about 90 percent of the total, was entirely free 

 from vitamine. The insoluble fraction, after decomposition with 

 neutral lead acetate, was very active. The liquid, freed from ex- 

 cess of lead and evaporated in vacuo, left an entirely crystallin 

 residue. With this preparation curative tests were performed on 

 pigeons, with the results recorded below in the section on " physiol- 

 ogy of vitamines." This preparation is still a mixture of sub- 

 stances, however, the bulk of it being adenin. After the Sepa- 

 ration of adenin some inactive, crystallin substances were eliminated 

 with platinic chlorid and picrolonic acid. Finally the vitamine frac- 

 tion was obtained by means of mercuric chlorid in alcoholic sol. 



Autolysed yeast. As already recorded in one of my early 

 papers, alcoholic extraction presents the disadvantage of being very 

 incomplete, most of the vitamine remaining in the residue. On the 

 other hand it offers the advantage that a large proportion of the 

 impurities remain behind, Fractionations were therefore conducted 

 with autolyzed yeast which, according to Cooper, contains the same 

 amount of vitamine as original yeast. Here, also, the acetone- 

 method in its original form was applied, but then another difficulty 

 arose. The acetone-insoluble residue from the phosphotungstate 

 precipitate amounted not to 10 percent, as in the case of the alco- 



