20 NUTRITION FACTORS IN YEAST AND BACTERIA 



Net yeast Bac- 



No. Hydrolysates of Animal Proteins. 1 cc. used. growth in terjri 





11. Vitellin (egg yolk) ....... ..................... 



12. Liver globulin (beef) .......................... 



13. Liver albumin " .......................... 



14. Gelatin (commercial "Silver Label" brand) ..... 



15. Gelatin (prepared from bones and marrow) ...... 



16. Gelatin (prepared from bones without marrow) . . 



Hydrolysates of Vegetable Proteins. 1 cc. used. 



17. Edestin (hemp seed) .......................... 



18. Gliadin (wheat) .............................. 



19. Zein (corn) ................................... 



20. Glutelin (corn) ............................... 



21. Legumin (peas) ............................... 



22. Vicilin (peas) ................................. 



23. Legumelin (peas) ............................. 



24. Oryzenin (rice ................................ 



25. Hordein (barley) .............................. 



26. Yeast protein ........................ ......... 1.0 + 



-j- denotes growth. 



denotes slight growth. 



(under Bacterial column) denotes no growth. 



(under Yeast column) denotes that growth was same as control. 



( " " " ) " inhibition. 



Quantitative Results : We attempted to devise a method for 

 the determination of the amount of stimulation of the growth 

 of streptococci by centrifuging the bacteria, as is done in the 

 method for yeast described by Funk and Dubin. 7 This pro- 

 cedure, however, was found to be impractical, due to the dif- 

 ficulty of stopping the growth of bacteria, and also because of 

 the occasional precipitation of substances which were not due 

 to bacterial formation. 



A better method for comparative results was devised, based 

 on the change in hydrogen ion concentration due to the fer- 

 mentation of the glucose in the D.I.-G.S. medium by the strepto- 

 cocci. This change in hydrogen ion concentration was deter- 

 mined by means of the Sorenson 8 indicator method, using the 

 Clark and Lubs 9 indicator set. Cole and Jordan 10 used a similar 

 method for diagnosis, by fermentation tests, of the gonococcus, 

 meningococcus and other pathogenic organisms. 



The variation in hydrogen ion concentration, in all of our 

 tests, covered a range from a PH of 7.4 to a PH of 4.0. For this 

 test, we prepared standard solutions consisting of mixtures of 



