370 



STATE Zlj-^jy OF AGRICULTURE. 



but ratiier tlie amount of the "plastie food," i. e.. of those substances 

 used for c " ' :^ up the cell, that ha5 the greatest bearing upon the 

 final eonct- ..-n of products. From these few results we can draw 

 ^sierml coz :-!?::• ns, howerer. 



This fact is evidentlT of great practical importance. Applications of 

 this are made alreadv in the vinegar fermeitation. The German or 

 quick vinegar proc-ess woite wiih distilled diluted alcohol, which is 

 practieally free from nutrient substances, and yields a more concen- 

 trated vrnegar Than the French or Orleans proc-ess where wine, beer and 

 similar alcoholic fluids with plenty of food material are fermented. 



Could we not in the same way explain the rapid multiplication with 

 very little fermeitation by yeasts in aerated liquids? In the one case, 

 they have plenty of one special food substance, namely oxygen, and 

 ^tesce they foment very little: in the other case, where this food supply 

 is soc»n exhausted, they ferment much more completely. 



The p»roduction of one certain c-ompound may. however, depend upon 

 other factors than the food supply only. Sackett. Patten and Brown 

 (Mieh- Exp. Stati(Mi Bui. Xo. 4.3) noticed a much slower solveit action 

 of he -'-—' upon bone meal in bnjth or peptone solution than in aspara- 

 gitt i _ - _ _ n. This seems to be another example for better fermentation 

 with pc«orer food, but the curves plotted from the data show that this 

 is not the case. We have not, as in the other examples quoted, at first 

 a stronger action of the better nourished bacteria, but the broth cul- 

 ture is lowest from the start This indicates that in this case the vary- 

 ing food c-auses varying decompoQtions. probably there is some alkali 

 produced in broth, n«itralizing the soluble acid j^osj^ates. 



¥i^ 18. Soluble Phosphates Produced in Different Media. 



