ROBBINS: VITAMINS 119 



acid would cure a pellagra-like condition in the dog known as "black tongue" 

 and in 1938 Spies and coworkers reported that nicotinic acid was effective in 

 the treatment of human pellagra. During the course of Goldberger's work he 

 was able to produce a syndrome in rats which he called "rat pellagra." How- 

 ever, Gyorgy (1934 and 1935) at the Babies and Children's Hospital in 

 Cleveland determined that this condition was not cured by the pellagra-pre- 

 venting factor, by thiamine or by vitamin B2. It could be cured by particular 

 extracts of rice polishings, and he proposed that the deficiency in the food 

 causing this peculiar type of dermatitis was a new vitamin which he called 

 vitamin Bg. In 1938 vitamin Bq, later named pyridoxine, was isolated and 

 identified by Kuhn in Germany, Ichiba and Michi in Japan, Lepovsky in Cali- 

 fornia, Gyorgy in Ohio and Keresztesy and Stevens in New Jersey. It was 

 synthesized in 1939 by Harris and Folkers. Partial or complete deficiencies 

 for pyridoxine have been found for some bacteria, some yeasts and a good 

 many fungi. It too appears to be a vitamin needed by all living organisms. 



Biotin. Biotin is a white crystalline substance which in the form of its 

 methyl ester has the empirical formula C11H1SN2O3S. Its structural formula 

 is not yet known, and it has not been synthesized from simpler substances. It 

 may be obtained by a long and costly process of purification from natural prod- 

 ucts such as egg yolk or liver and for $10.00 you may purchase 75 micrograms 

 of pure biotin which is at the rate of about $62,400,000 per pound. It was first 

 isolated by Kogl and Tonnis of Utrecht in 1936 from the yolk of eggs and has 

 proved to be the most potent of all the vitamins. Kogl and Fries were able to 

 detect the effect on the growth of a fungus of 0.0001 of a microgram of biotin 

 methyl ester. Biotin is widely distributed in products of natural origin. We 

 have found it in such unexpected places as cow manure and cotton. In fact, 

 a bale of cotton contains about $1000 worth of biotin. It is made by green 

 plants and many bacteria, yeasts and filamentous fungi. There are, however, a 

 good many of the lower organisms which lack the ability to make biotin ; 

 some cog is missing in their machinery, or it works slowly, and these organisms 

 grow poorly or not at all in media from which this vitamin is absent. It is 

 probably essential for animal growth and from recent pronouncements in vari- 

 ous journals may be intimately associated with the development of cancer. 



The discovery of biotin has a long and interesting history. In 1860 Pasteur 

 published an important memoir on alcoholic fermentation in which he came to 

 the conclusion that yeast grew if supplied with yeast ash, ammonium salts and 

 a fermentable sugar. He observed that the fermentative power of yeast was in- 

 creased by the addition of extracts from natural products, for example, grape 

 juice, sugar beet juice or yeast juice but all the essentials for growth were 

 included, according to Pasteur, in a solution of yeast ash, ammonium salts 

 and glucose. However, in 1869 the famous German chemist, Justus von Liebig, 



