70 Dairy Bacteriology. 



68. Other kinds of colored milk. Two or three 

 chromogenic forms producing still other colors have been 

 found in milk. Schroeter discovered in a sample of 

 cooked milk, a peculiar form (Bacillus synxanthus) that 

 produced a citron yellow appearance and which precipi- 

 tated and finally dissolved the casein. Adametz, 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- producing bacteria, such as those 

 that produce violet or green changes in the milk have 

 been observed. 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 of it except 

 in occasional instances. 



69. Treatment of milk fermentations. Attention 

 has already been drawn to the distinction that should be 

 made between taints due to fermentative action caused by 

 the absorption of some pre-existing odor. In treating 

 any abnormal fermentation, the attempt should first be 

 made to locate the cause of the trouble. In most in- 

 stances where the difficulty is due to bacteria, it is caused by 

 foreign matter gaining access to the milk. Scrupulous 

 cleanliness will therefore in most cases eliminate the 

 trouble and the suggestions made in Chapter IV as to 

 the methods of preventing bacterial infection will be help- 

 ful in this connection. So efficacious is this course that 

 cleanliness in every detail in dairy pursuits is almost a 

 panacea for troubles and taints of all sorts that occur in 

 milk. 



If the taint is recognized in the mixed milk of the herd, 

 it is necessary to ascertain, first, whether it is a general 



