320 THE FERMENTATION OF CHEESE. 



land) soft " household " cheese, in addition to Emmenthal cheese 

 led to the following results : 



(i.) The freshly precipitated curd, moulded in the press and 

 freed from excess of whey, contains between 90,000 and 140,000 

 bacteria per i gram, a comparatively large number of these being 

 able to liquefy gelatin, and consequently excreting a peptic 

 ferment. 



(2.) During the period of ripening, the germ content gradually 

 rose to 850,000 in Emmenthal cheese and up to 5,600,000 in the 

 " household " cheese, but only a small share in this increase fell 

 to the liquefactive species ; since whilst the quantitative ratio of 

 these to the other (non-liquefactive) kinds was in the fresh curd 

 i : 40, only one colony of liquefactive bacteria was found in 150 to 

 1 80 in the gelatin plate cultures prepared from the ripe cheese. 



The expectation of rinding the liquefactive bacteria assume the 

 upper hand during the ripening process was thus dispelled, and 

 the same result was attained in a later research published by K. 

 VON EREUDENREICH (IV.) in 1894, according to whom the number 

 of lactic acid bacteria in cheese increases with the age of the latter. 

 Hence the chief, if not the sole, share in the ripening of Emmen- 

 thal cheese must be ascribed to these lactic ferments. E. J. 

 LLOYD (I.) also came to the same opinion in his researches on the 

 ripening of Cheddar cheese. 



The reason why Duclaux, in his earlier investigations, arrived 

 at a contrary result will be readily understood when it is remem- 

 bered that he prepared his pure cultures exclusively by the dilution 

 method, and therefore by the aid of liquid nutrient media (bouillon 

 in particular) ; since in this last-named liquid the organisms of the 

 genus Tyrotlvrix thrive exceedingly, whereas the lactic acid bacteria 

 grow badly, if at all, therein. Consequently mixed sowings in 

 this medium result in a preponderance of the liquefactive species 

 described by Duclaux. From the discovery made by FREUDENREICH 

 and SCHAFFER (I.) that the ripening of hard Swiss cheese also 

 goes on uniformly throughout the mass when air is excluded, 

 it follows that the said lactic acid bacteria are (facultatively) 

 anaerobic. 



The harmonious results of the researches of M. LANG and 

 FREUDENREICH (I.) with Swiss, and of E. MARCHAL (III.) with 

 Belgian (Limburg), samples show that a principal part in the 

 ripening of soft cheese is taken by Outturn lactis, further particu- 

 lars of which member of the Eumycetes group will be found in 

 the second volume. Various budding fungi also seem to aid in 

 the process, but more detailed information on this point is absent. 

 According to the statements of JUL. HENRICI (I.), Swiss cheeses are 

 poor in yeast-like fungi and rich in bacteria; but the converse 

 ratio has been shown to exist in American cheeses. 



Odour is one of the characteristics peculiar to individual kinds 

 of cheese ; it is but slightly developed in many, but is prominent 



