1916] DAIRY FARMING DAIRYING. 675 



In 32 samples, bacteria were not multiplying in numbers worth considering. 

 Three types of bacteria were found commonly present in milk from all five dairies ; 

 they were streptococci, staphylococci, and bacilli. The ordinary milk-souring 

 organism, Streptococcus lacticus, was not found in any of the samples of milk. 

 It does not appear to localize and multiply in the udder. Long-chained strepto- 

 cocci which failed to give the reduction of litmus in milk cultures characteristic 

 for S. lacticus were isolated from 29 samples. The highest number found per 

 cubic centimeter was 2G4,000. Micrococci were found in 113 samples, the high- 

 est number found per cubic centimeter being 80,000. 



The majority of the micrococci were shown to belong to one group, which 

 agrees in characteristics with the pyogenic staphylococci. The majority of cul- 

 tures of this type were nonvirulent, but some cultures were virulent, and two 

 cultures possessed such a high degree of virulence that inoculated rabbits died 

 in about 16 hours. Three other types of micrococci from the udder gave reac- 

 tions which differed from those of the pyogenic staphylococci sufficiently to sep- 

 arate them into distinct groups. One of these groups is described, but no name 

 is suggested for it because of the small number of cultures studied. Another 

 group was identified with Micrococcus luteus, according to Winslow's classifica- 

 tion. The third group was characterized by the rapid and complete peptoniza- 

 tion of milk, and the name M. caseolyticus is suggested for this group. 



Peculiar strains of the types of bacteria commonly present in freshly drawn 

 milk were sometimes found localized in the udders of several cows of one 

 dairy. A few cases were found of peculiar species, unlike any of the other 

 udder organisms, localized in this same way. 



The bacilli commonly present in milk from all five dairies were shown to 

 be related to Bacillus abortus. Three varieties of this type were distin- 

 guished. The variety occurring most frequently was designated B. abortus, 

 variety lipolyticus, because it decomposes milk fat. In its cultural character- 

 istics this variety agrees closely with Bang's original description of B. abortus. 

 Cultures of this variety were shown to be capable of imparting undesirable 

 flavors and odors to cream kept under conditions to which cream is frequently 

 subjected. Two other varieties of B. abortus type differed considerably from 

 the lipolyticus variety, but resembled the cultures isolated from pathogenic 

 sources and studied for comparison. Cultures of B. abortus type were isolated 

 from 45 of the 192 samples studied. The highest number of these bacilli 

 found per cubic centimeter was 50,000. 



The author concludes that " there is a definite udder flora comprising bacteria 

 which belong to parasitic types. It is not surprising that the majority of udder 

 bacteria should be of the same type as those common on the skin and mucous 

 membrane of man and animals. The majority of the staphylococci on the skin 

 are of the nonvirulent variety, which fails to produce pigment and fails to 

 ferment mannite. But pathogenic varieties also are found on the skin, where 

 they ordinarily cause no trouble. Similarly, the majority of the staphylococci 

 of the udder are nonvirulent, but varieties which are capable of causing death 

 when inoculated into experimental animals occasionally establish themselves 

 in healthy udders. Whatever the variety may be, conditions in the udder are 

 favorable to multiplication, and frequently large numbers are eliminated in the 

 milk. 



" The pathogenic properties of the streptococci and bacilli common in milk 

 when it leaves the udder are not discussed in this paper, but they also are 

 parasitic in their nature. 



" When a bacterial culture is tested for its pathogenic properties the body 

 tissues and fluids are exposed directly to the toxins of the culture in question. 

 When organisms enter into the digestive tract with the food the circumstances 



