11 



On the 26th of November, 1902, 80 cc. of sterilized milk were inoculated with 

 2 oese of a 24-hour old bouillon culture of the lactic acid bacillus; and plates 

 made from this mixture gave 430 colonies per oese. On the 3rd of December, 

 this milk, at a temperature of 40 degrees Fah., was again examined and showed 

 ISO colonies per oese; and at the same time, one drop of the milk was diluted 

 in 12 cc. of sterilized water and two colonies per cc. of this mixture developed. 

 On the i6th of December, the temperature being the same, 42 colonies per 

 cc. and 2 colonies per oese respectively developed. The milk was then trans- 

 ferred to the incubator at 20 degrees C, and coagulated in 24 hours. Other 

 experiments with gas-producing germs had similar results — there was no in- 

 crease in the number of bacteria held at 40 degrees Fah. This experiment was 

 repeated with lactic acid bacteria and gas-producing bacteria, with similar 

 results, viz., that there was no increase in the numbers of bacteria in milk held 

 at 40 degrees Fah. Consequently, there could be no increase in the number 

 of lactic <Qcid and gas-producing bacteria in cheese held at this temperature. 



Bacterial Contents and Ripening Phenomena. 



Bacterial Contents and Ripening Phenomena. The question of the really 

 active agent or agents in the curing of cheese is still an open one. If bac- 

 teria are the active agents, then lactic acid bacteria must be the agents in the 

 process. De Freudenreich appears to have shown that these bacteria can 

 produce an increase of the soluble nitrogenous products ili the casein of milk, 

 provided calcium carbonate is present. Klein and Kirsten stated that, by the 

 use of starters, normal cheese can be made from pasteurized milk (which is 

 free from enzymes); but Boekhout and Vries were unable to produce normal 

 Edam cheese 'from aseptic milk with the addition of a culture of the lactic acid 

 bacillus; and Chodat and Bang did not obtain an increase in the quantity of 

 soluble nitrogen by growing lactic acid bacteria on coagulated casein; so, tak- 

 ing these facts into account, we are bound to admit that there still exists more 

 or less doubt as to the ability of the lactic acid bacillus alone to produce an 

 increase in the amount of soluble nitrogen. 



Babcock and Russell attributed to Galactase (an enzyme which they dis- 

 covered in milk) the principal influence in the ripening of cheese; but De 

 Freudenreich has shown that 0.5 per cent, of lactic acid enfeebles the action 

 of galactase; and the very considerable amount of acid in normal Canadian 

 Cheddar cheese must still more diminish the action of this ferment, as the 

 percentage of acidity or acid salts in ordinary cheese of this kind varies at 

 different ages from 0.76 per cent, to 1.5 per cent. 



Babcock and Russell (subsequent to the discovery of Galactase) and Jensen 

 simultaneously proved that the pepsin in rennet increased the higher decom- 

 position products, such as albumoses and peptones, in cheese; and there is 

 the well-known fact that cheese-makers increase the amount of rennet when 

 they want a fast-curing cheese. 



Rennet acts more quickly and better than galactase in acid solutions; and 

 it seems that the function of the lactic acid bacteria, whose growth in milk is 



