Fermentations in Milk. 75 



particles of bluish or grey color, which later become con- 

 fluent, the blue color increasing in intensity as the acidity 

 increases. The causal organism, B. cyanogenes, is very re- 

 sistant toward drying, 1 thus accounting for its persistence. 

 In Mecklenberg an outbreak of this sort once continued 

 for several years. It has frequently been observed in Eu- 

 rope in the past, but is not now so often reported. Occa- 

 sional outbreaks have been reported in this country. 



Other kinds of colored milk. Two or three chromo- 

 genic forms producing still other colors have occasionally 

 been found in milk. Adametz 9 discovered in a sample of 

 cooked milk a peculiar form (Bacillus synxanthus) that 

 produced a citron-yellow appearance which precipitated 

 and finally rendered soluble the casein. Adanietz, Conn, 

 and List have described other species that confer tints of 

 yellow on milk. Some of these are bright lemon, others 

 orange, and some amber in color. 



Still other color-producin 8 bacteria, such as those that 

 produce violet or green changes in the milk, have been ob- 

 served. In fact, almost any of the chromogenic bacteria 

 are able to produce their color changes in milk as it is such 

 an excellent food medium. Under ordinary conditions, 

 these do not gain access to milk in sufficient numbers so 

 that they modify the appearance ot it except in occa.jional 

 instances. 



Treatment of abnormal fermentations. If the taint is 

 recognized as of bacterial origin (see p. 57) and is found in 

 the mixed milk of the herd, it is necessary to ascertain, 

 first, whether it is a general trouble, or restricted to one or 

 more animals. This can sometimes be done by separating 



J Helm, Arb. a. d. Kais. Gesundheitsamte, 5:578. 

 a Adametz, Milch Zeit., 1890, p. 225. 



