450 S. HENRY AYERS AND COURTLAND S. IIUDGE 



with the water-soluble vitamine B and the fat-soluble vitamine 

 A in their relation to the growth of a streptococcus. 



EXPERIMENTS WITH WATER-SOLUBLE B 



Throughout our experiments we have used a culture of a patho- 

 genic streptococcus which grew slowly in a peptone yeast medium. 

 This organism would not grow in a peptone medium without 

 broth, and the fact that it would grow with the addition of yeast 

 extract brought up the possibility that the water-soluble B might 

 be the reason for the growth. 



Several experiments were conducted in order to throw some 

 Ught on this point. In the first experiment 10 grams of autohzed 

 yeast were extracted in a Soxhlet apparatus for eight hours with 

 95 per cent alcohol. Fresh alcohol was then added and the ex- 

 traction continued for another eight hours. This process was 

 repeated until the extraction had been continued for forty hours. 

 During the extraction the yeast was removed several times from 

 the thimble and the clumps were thoroughly disintegrated. As 

 the alcohol was removed during the extraction it was evaporated 

 at a temperature of G0° to 80°C. The combined residues from 

 the successive extractions were added to 500 cc. of distilled water 

 and heated for a half hour. To this was added an equal amount 

 of 2 per cent Difco peptone and the reaction adjusted to pH 7.2. 

 This medium was then steamed for fifteen minutes, filtered, 

 placed in flasks, and sterilized. The residue from the original 

 10 grams of yeast which had undergone extraction by the 95 per 

 cent alcohol was added to 500 cc. of distilled water and another 

 medium prepared with Difco peptone as described. A third 

 medium was prepared by using 10 grams of the regular autolized 

 yeast which had not been extracted. This was added to 500 cc. 

 of distilled water and a medium prepared with Difco peptone, 

 the same as with the other media. In all the experiments the 

 media were distributed in 50 cc. amounts in 100-cc. Erlenmeyer 

 flasks. These flasks were approximately of the same shape so 

 that the depth of the medium and the surface area exposed was 

 about the same in each flask. 



