ii8 Transactions of the Canadian Institltk. |\'ol. VII. 



produced b)- bacteria capable of action on casein, but ev^en bacteria 

 themselves or even their spores might contain digesting enzymes. 

 De Freudenreich does not believe with Babcock and Russell that 

 galactase pla}s the principal role in the ripening of cheese, but that 

 in rendering the casein soluble, it probabl}' prepares for and facilitates 

 the work of the bacteria which cause the ripening, and the special taste 

 of cheese. 



Jensen studied the origin and properties of the enzymes found in 

 cheese, both hard (Emmenthaler) and soft (Limbourg) varieties. To 

 determine if galactase pla}'ed any part in the ripening, he examined the 

 following four points : 



1. Is the galactase of milk in sufficient quantit}' in the curd to be 

 able to produce an appreciable transformation of the casein? 



2. How long does galactase remain in the cheese ? 



3. Are the natural conditions met with in cheese such, that the 

 galactase can exercise its action ? 



4. Does the pepsin of the rennet take part in the ripening of cheese? 



By a series of analyses, too long to quote in this paper, Jensen 

 partially answered the above questions. Thus he concluded : 



1. As cheese is made with rennet, galactase and the pepsin in rennet 

 are present in sufficient quantities to produce changes in the casein. 



2. Soft cheese is richer in enzymes than hard cheese. 



3. The quantit}' of free lactic acid in soft cheese is sufficient to 

 hinder the action of galactase, and consequenth' favour the action of the 

 pepsin. In hard cheese, on the contrary, the quantity of free lactic acid 

 present is smaller and only helps in a slight degree the action of pepsin 

 at the expense of the galactase. 



To determine which of the two factors, the lactic ferments or 

 galactase, plays the principal role in the ripening of Emmenthaler 

 cheese, Jensen compared the changes which naturally occurred in the 

 casein of cheese with those caused b\' each of the two factors above 

 mentioned. The action of galactase was rendered insignificant b\' using 

 one per cent, of Formalin to prohibit bacterial action. Whilst to show 

 the action of this enzyme, fifteen to twenty per cent, of ether was used 

 to destroy the bacterial life. Again, the chief function of galactase is in 

 its rendering albuminoid substances .soluble, and the principal role of the 



