igoo-i.] Thk Ripening of Cheesk. 127 



3. The oldest cheese analyzed was fifty-one days old. Russell gave 

 the result up to 108 days for two cheeses, and up to 237 days for one. 



The general results of these studies on Canadian cheese are shown 

 by the diagram and tables, and demonstrate the enormous increase 

 of the lactic acid bacteria in the initial stages of cheese-making. From 

 the moment the milk is placed in the vat, every condition favourable for 

 the growth of this class of micro-organism is carefully fostered. The 

 greatest number found was in cheese two or three days old ; at this age, 

 one cheese contained 520 millions bacteria per gram, nearly five times 

 as many as Russell observed in Wisconsin cheese. 



From this point the numbers decline at first rather rapidly, but 

 subsequently the decrease is more gradual. 



Comparing my results with Russell's and summarizing them, I 

 might state that in Canadian Cheddar cheese there is : 



1. Period of increase in which the bacteria develop most rapidly in 

 the curd, and in the cheese up to the age of two or three days, followed 

 by 



2. Period of rapid decline, in which the numbers fall away somewhat 

 rapidly until about the thirteenth day, when the cheese may be said to 

 enter the final 



3. Period of slow or general decline, in which their numbers slowly 

 decrease, at the 430th day but 1,400 per gram were found. 



The results, whilst agreeing with Russell's, as to the enormous 

 development of the lactic acid bacteria in cheese, differ in that there is 

 no period of "Initial Decline," and that the "Period of Increase" 

 virtually takes place in the curd. The maximum number are present 

 in the cheese at the moment it is taken out of the press. The "Period 

 of Final Decline," I have subdivided, although my two divisions may be 

 quite well taken together. 



If in connection with this remarkable increase of lactic acid bacteria, 

 we examine the amount of acid present in the curd and cheese, we find 

 that the greatest increase in acidity occurs between milling and salting. 

 From this point until the cheese is forty days old there is a gradual and 

 progressive increase. Thus, the increase in acidity from the time of 

 milling until the cheese was six days old was 0.32 per cent, calculated 

 as lactic acid, and the increase from the latter age to forty-one days old 



