3o6 Vitamines and Deficiency Diseases [June-September 



theory of Schaumann had to be abandoned when it was shown, in 

 my early experiments with yeast, that, after hydrolysis for 24 hr., 

 with 20 percent sulfuric acid sol., yeast retained its curative prop- 

 erties. The experimental data indicated that the active substance 

 was comparatively simple in chemical nature, more or less basic in 

 character and, to some extent, thermostable in acid Solution. 



On the assumption that the active substance contains nitrogen, 

 the alcoholic extracts of different foodstuffs were fractioned by 

 means of the usual methods for the Separation of organic bases. 

 Chemical attention, however, was chiefly devoted to extracts froni 

 yeast and rice-polishings. It was found that vitamine was precipi- 

 tated with phosphotungstic acid, partially with mercuric chlorid in 

 alcoholic sol., and with silver nitrate and baryta, the latter precipita- 

 tion proving to be the best for the Isolation of vitamine. The cura- 

 tive fraction obtained in this way was very small — between 3-5 gm. 

 from 100 k. of dry yeast, or locx) k. of rice polishings. 



This fraction, administered orally or subcutaneously to beriberi 

 pigeons, exhibited the following effects : The animals recovered very 

 speedily, often in 2-3 hr., but it was found impossible to keep them 

 permanently on polished rice even when injections were repeated 

 every few days. By further f ractioning the curative material from 

 yeast, three substances were obtained. One was definitely identified 

 as nicotinic acid. The second substance, when completely purified, 

 proved to be inactive but represents without doübt a new chemical 

 substance; this is now undergoing a complete investigation. The 

 third substance was obtained only in traces. None of these three 

 products, given either separately or together, showed anything like 

 the action of the original fraction. Thus far rice-polishings, as we 

 shall see later in this resume, have yielded nothing in this connection 

 but nicotinic acid. It does not seem improbable that this substance 

 is a decomposition product of an unstable vitamine. 



It is not surprising that little has been achieved in the elucidation 

 of the chemical structure of these puzzling substances. In their 

 study unusual experimental difficulties are encountered which will 

 be discussed below. Even a relatively simple problem like the 

 chemical structure of adrenalin required a series of years for 

 Solution. 



