BACTERIA COMMONLY FOUND IN COWS' MILK. 97 



several weeks it was impossible to prepare satisfactory 

 sour milk on this farm, although the pans were finally 

 placed in another room and the vessels were carefully 

 cleaned. At last they began to inoculate the milk with 

 ordinary sour buttermilk, and after a considerable time 

 succeeded in this manner in making common sour milk. 

 Not till late in the fall did the milk again turn sour in 

 the ordinary way, without any separate inoculation being 

 necessary. 



The greenish-blue skim-milk in the first unsuccessful 

 sour milk gave a very distinct alkaline reaction and con- 

 tained a large number of bactei-ia, among which a short, 

 staff-like bacillus was especially noticeable. By pure cult- 

 ures of this bacteria it was learned that it was in the main 

 similar to the blue-milk bacillus (Bacillus cyanogenus) 

 common in Germany, and more particularly similar to the 

 form of it first investigated by Hueppe, and claimed by 

 him to be the typical and regular cause of blue milk. This 

 has been studied again of late by Scholl, and duly char- 

 acterized as a variety (or species) distinctly different from 

 the forms described by Loffler and others. It does not 

 peptonize gelatine, but produces in the same a fine green 

 coloring-matter resembling chlorophyll; the other kinds 

 of bacteria produce a brownish coloration in gelatine. 

 Neither the bacterium isolated by me nor the blue-milk 

 bacteria found in Germany caused coagulation or fermen- 

 tation of acid when inoculated in sterile milk; it was some- 

 times observed that the milk was for a while viscous and 

 thick-flowing. This, however, seemed soon to disappear. 

 The milk turned alkaline if it previously was weakly acid 

 or neutral. I have been unable to observe any blue colora- 

 tion of the surface of the milk; the lower layers of the 



