130 THE VITAMINS 



the ration can be supplemented by untreated or autoclaved brewers' 

 yeast (2^ hours at 15 pounds pressure), and by the residue left after 

 preparing the Osborne- Wakeman fraction II from fresh brewers' yeast 

 (a product deficient in both vitamins B and G) led them to believe 

 that these latter materials contain a new factor only slightly soluble in 

 water or in hot 85 to 90 per cent alcohol, a factor similar to but not 

 identical with that discovered by Smith and Hendrick (1926) and by 

 Goldberger and his colleagues (1926). It appeared to be present in dried 

 boiled beef, egg white, summer milk, and the casein and butter of 

 summer milk, but not to any extent in wheat embryo or yeast extracts. 

 According to their work, this material can be extracted from the feces 

 of rats by hot 90 per cent alcohol in 24 to 32 hours, appears to be in- 

 soluble in ether, and seems less stable to heat in feces than in yeast. 



Hunt (1928b) also reported the presence of a factor in the auto- 

 claved residue of washed autolyzed yeast which supplements the growth 

 promoting value of vitamin B and vitamin G concentrates. 



Reader (1928, 1929, 1929a, 1930) has demonstrated the existence 

 (in a yeast preparation and in the mercuric sulfate precipitate of the 

 Kinnersley and Peters' process of concentrating vitamin B) of a factor 

 alkali-labile and more thermolabile than vitamin B (Bi) without which 

 the growth of young rats fails in 4 or 5 weeks when placed at weaning 

 on a basal diet reinforced with vitamins A, Bi (B), B2 (G), and D. 



Coward and her coworkers (1929) announced the existence of a 

 factor distinct from vitamins A, Bi (B), B2 (G), D, and E, not present 

 to an appreciable extent in dry yeast or marmite but associated with 

 fresh milk, certain caseins, grass, ox muscle, ox liver, and wheat em- 

 bryo. This factor appears to be relatively insoluble in cold 2 per cent 

 acetic acid, 97 per cent alcohol, or ether, but some of it was extracted 

 from certain caseins and to a greater degree from wheat embryo, by 

 four successive extractions of 6 hours each with hot alcohol or ether. 

 Simmering fresh milk for 15 minutes appeared to reduce its potency; 

 the value of dry casein was somewhat lowered by heating for seven 

 days at 107° C., but not (measurably) by such heating for one day. 

 The appearance of a deficiency of this factor was evident at an earlier 

 age in animals used in vitamin B experiments than in those used in 

 vitamin A studies. 



Chick and Roscoe ( 1929) observed that egg white although a good 

 source of vitamin G (B2, antidermatitis factor) lacks some growth 

 essential present in autoclaved yeast. In a few instances when egg white 

 was used as a source of vitamin G (B2) the growth of rats was in- 

 hibited by the sixth or seventh week of age, but it usually remained 



