igoo-i.] The Ripening of Cheese. 105 



Cantal cheese, and was able to study them in pure culture. The 

 dilution method of culture was then in vogue, and some writers have 

 criticised the accuracy of his work on this account. Not only did 

 Duclaux isolate a large number of species, but he was able to contribute 

 other interesting details as to form, spore formation, aerobic and 

 anaerobic characters, physiology, and the nature of the fermentation 

 products of the different micro-organisms, that he studied. To all 

 species isolated, he gave the generic name Tyrothrix (cheese-threads), 

 and of these seven were aerobic and three anaerobic. All but one of 

 these germs possessed the ability of coagulating the casein ; and, 

 subsequently digesting the coagulum. From one of the most energetic 

 of these bacteria (Tyrothrix tenuis) Duclaux isolated a ferment which 

 was able to convert the casein into a soluble peptone. This he called 

 casease and the product of its action on casein he named " caseone " ; 

 this latter substance might be even further split up into other substances, 

 as leucin and tyrosin. Several of the other species isolated also 

 produced the last named substances. 



Adametz, working at Sornthal, in Switzerland, in 1889, upon 

 Emmenthaler and Cottage cheese (a soft variety) isolated nineteen 

 different, well characterized schizomycetes and three yeasts. Of the 

 first, seventeen were new species and were supposed to influence the 

 ripening process. Contrary to previous investigations, neither B. subtilis 

 nor B. butyricus was found. He divided these bacteria into three 

 groups. 



(a). Such as dissolved the paracasein, or changed it to a peculiar 

 spongy condition. Soluble albuminoids and peptones were produced in 

 greater or less quantities at the same time, and these were accompanied 

 by traces of smelling {e.g., Butyric acid) and tasting {e.g., bitter extractive 

 matters) substances. 



(b). Such as developed slowly in sterilized milk, and for which 

 unchanged paracasein was not a favorable soil, but they easily 

 assimilated the substances produced by the first group. 



(c). Such as had no appreciable effect upon any of the nutritive 

 substances herein concerned, and whose presence or absence made no 

 difference to the ripening of the cheese. 



The Cottage cheese was distinguished bacteriologically from 

 Emmenthaler by the following points : 



I. The larger bacterial content (in one gram of Emmenthaler 

 850,000 germs, and in one gram of Cottage cheese 5,600,000 bacteria). 



