472 



STATE BOARD OF AGRICULTURE. 



TABLE XVII. — Influejice of Peptone on Strain IV. 



The fermenting- capacity is higher in two cases with peptone and in 

 one case without peptone, and the differences are not vei-y pronounced, 

 so it seems quite safe to state that the fermenting power of each cell 

 was not altered materially while the reproduction was stimulated de- 

 cidedly. The most remarkable effect produced by the peptone, however, 

 remains unexplained, namely the higher number of bacteria and the 

 higher final acidity. It is generally assumed that fermentation ceases be- 

 cause the products of fermentation interfere with a continued activity of 

 the fermenting enzyme. If Strain IV normally ceases to ferment at 

 60° acid, why does it produce twice that amount in the presence of pep- 

 tone? And why does only Strain IV show this difference while vStrain 

 II does not. The question could be solved by the assumption that in the 

 presence of peptone, a more resistant lactacidase is formed, but another 

 simpler explanation is possible, based on the law of mass action. It is 

 kno^Ti that, at least with some enzymes, the enzymic action will I'eacli 

 an equilibrium. If this equilibrium is disturbed by further addition of 

 enzyme, enzymic action Avill continue for a ccx^tain time. In the case 

 of Strain II, the number of cells and the amount of enzyme per cell was 

 found to be constant, consequently there is a constant amount of acid 

 produced. In the case of Strain IV, the number of cells in one sample 

 is five times as high as in the other. The individual cells of each of the 

 two samples were found to contain approximately the same amount of 

 enzyme, consequently there is five times as much enzyme in the one 

 flask as in the other. Under these conditions, the equilibrium in the 

 two flasks cannot be expected to be the same. It is by no means certain, 

 however, that the law which is found true with a few enzymes holds 

 true with all of them, and it seems still doubtful whether the amount of 

 fermentation products in a culture can be increased by adding large 

 quantities of cells. 



The increase in the number of bacteria by the addition of peptone does 

 not agree with the common assumption that the number of cells is limited 

 by the accumulation of fermentation products. An explanation seems 

 l>ossible Avhich at the same time helps to account for the results in an- 

 other experiment. Strain II is not afl'ected by peptone, so we must con- 

 clude it is able to provide for its nitrogenous matter in some other way, 

 or it is not able to use peptone. Its development in milk seems to be 



