380 JAMES M. SHERMAN 



bacteria were found but they did not appear to have much in- 

 fluence on the ripening of cheese. 



In the early experiments conducted by the Department of 

 Agriculture on Swiss cheese, some cultures of propionic acid 

 bacteria were obtained from Professor Burri of Berne in the hope 

 that these could be introduced and used in the manufacture of 

 Swiss cheese in this country. The experiments conducted with 

 these cultures, however, were not encouraging; in fact it was not 

 established experimentally that they were able to cause the devel- 

 opment of eyes when used for starters in the manufacture of Swiss 

 cheese. Following the methods of Von Freudenrich and Orla- 

 Jensen, cultures were isolated which corresponded to their pub- 

 lished descriptions of the propionic-acid bacteria. These were 

 also used in the manufacture of experimental Swiss cheese with 

 negative results. These findings do not discredit the work of Von 

 Freudenrich and Orla-Jensen, since it is entirely possible that the 

 cultures used belonged to varieties which do not play important 

 roles in the ripening of Emmental cheese. The experiments re- 

 ferred to were carried on a few years after the death of Professor 

 von Freudenrich; Professor Orla-Jensen at that time was not 

 able to furnish cultures of these organisms. 



I. CONCERNING THE OCCURRENCE AND NUMBERS OF LACTATE- 

 FERMENTING BACTERIA IN EMMENTAL CHEESE 



That there exist in Emmental or Swiss cheese bacteria which 

 ferment lactates with the production of volatile acids has been 

 shown by Von Freudenrich and Orla-Jensen (1906), who suc- 

 ceeded in isolating such organisms in pure culture ; and the theory 

 was advanced that the production of eyes is due to the carbon 

 dioxide liberated by these bacteria in the transformation of lactic 

 acid to propionic and acetic acids, according to the formula: 



3 C3H6O3 = 2C3H6O3+C2H4O2+CO2 + H2O. 



They also determined the approximate number of lactate- 

 fermenting organisms in Emmental cheese by means of dilution 

 cultures in a calcium lactate broth. By such methods they were 



