VITAMINES AND GROWTH OF STREPTOCOCCUS 453 



and sterilized as described above. Osborn and Wakcman found 

 that fraction II contained most of the water-soluble B, and that 

 fractions I and III contained some. According to this we should 

 expect that the peptone medium containing fraction II should 

 contain most of the water-soluble B, that the medium containing 

 fraction I should contain less, and that filtrate A should contain 

 the least or none at all. On this assumption, that water-soluble 

 B is the growth-promoting substance of yeast, it would be expected 

 that media containing fraction II would give the best growth 

 with the streptococcus. From the second section of table I it 

 will be seen that such was not the case. There was no growth in 

 peptone media containing fraction II or fraction I, but there 

 was growth in the peptone medium containing filtrate A. These 

 results seem to confirm those obtained in the first experiment and 

 again indicate that water-soluble B is not the growth-promoting 

 substance of yeast. 



A third experiment was conducted in which the water-soluble 

 B was considerably reduced and possibly entirelj'' removed from 

 the j'^east extract. Seidell (1916) has shown that, by shaking 

 autolized yeast extract with Lloyd's Reagent (Fuller's Earth) 

 using 50 grams per liter of extract, only an inconsiderable amount 

 of the vitamine appeared to remain in the filtrate. Ten grams 

 autolized yeast were added to 200 cc. of distilled water. This 

 was allowed to stand for about one hour with frequent shaking 

 before filtering. To this filtrate 50 grams of Lloyd's Reagent 

 were added together with HCl to make the solution 0.01 normal. 

 The yeast extract was then shaken every half hour for four hours 

 and the Lloyd's Reagent removed by filtration. The Lloyd's 

 Reagent was supplied to us through the kindness of Dr. Seidell 

 and was known to be an active grade of Fuller's Earth. The 

 filtrate was made up to 1000 cc. to which 1 per cent of Difco 

 peptone was added and the reaction adjusted to pH 7.2. After 

 filtration this medium was put in flasks and sterilized in the usual 

 way in the autoclave. Since it has been found that the Lloyd's 

 Reagent removes a large part, if not all, of the water-soluble B 

 from yeast extract it would be expected that a peptone medium 

 containing a yeast extract treated with this substance would not 



