GROWTH 



241 



other sources. All conditions being exactly alike, the 

 crops obtained per 100 gm. of sugar used were: 



From molasses 



+ ammonia, 



gm. 



From molasses 



+ peanut meal, 



gm. 



From molasses 



+ malt sprouts, 



gm. 



With slow aeration 98 . 8 



With rapid aeration. . . 113 . 2 



139.8 

 216.8 



110.4 

 144.7 



With ammonia as the only source of nitrogen, molasses 

 being substituted by sucrose, the crop was only 69.0 

 gm. (Exp. 7). Asparagin (Exp. 8) and aspartic acid 

 (Exp. 9) gave better crops, 83.5 and 93.9 gm. The 

 total available nitrogen was only 4 gm. against 4.9 gm. 

 in the six previous experiments. 



Another set of comparable data are experiments 18 

 to 21, with 3.6 gm. of total assimilable nitrogen and 1.8% 

 sucrose instead of molasses. The crops were: 



Gm. 



With ammonium phosphate 75 . 8 



With peanut meal 140.2 



With malt sprouts 104 . 5 



Half ammonium phosphate, half peanut meal 136 . 7 



These results probably mean that the protein material 

 of the peanut extract was most similar to that of the 

 yeast, and that with the same amount of energy, the 

 yeast could grow more rapidly, and therefore reach a 

 higher final crop. The surprising fact is that with half 

 the amount of peanut extract, and the rest of nitrogen 

 substituted by ammonia, the yeast reached practically 

 the same weight, 136.7 gm., and had about the same 

 nitrogen content, the same keeping quality and a better 

 fermentative action. This shows that while it is uneco- 



