488 CATTLE DISEASES TRANSMISSIBLE THROUGH MILK 



discussed in Kitt's contribution on this subject to Kolle and Wasser- 

 mann's Manual on Pathogenic Microorganisms. L. Frank was the 

 first investigator to hold that mastitis in cows was generally due to an 

 infection, and, in 1875, he conducted experiments showing that the 

 disease could be produced by injecting fluids containing certain 

 bacteria into the udder, and that it could then be again transferred 

 from diseased to healthy cows. The bacteriology of bovine mastitis 

 was subsequently studied by a large number of authors, among whom 

 may be mentioned Rivolta, Dickerhoff, Mollereau, Nocard, Kitt, 

 Bang, Lucet, Guillebeau, Jensen, and others. The disease may have 

 a very rapid onset (over night), and it may then become chronic or it 

 may from the beginning have an insidious, slow, and chronic course. 

 The milk, in cases of very acute onset, shows marked changes; it 

 often contains coagula, which are sometimes stained by admixture 

 with blood. In the slow, chronic cases not much change is evident 

 in the lacteal fluid. Sometimes one-quarter of the udder alone is 

 affected, at other times two, three, or all of the four ventricles. Some- 

 times mastitis leads to grave general symptoms, with high fever and 

 prostration. Recovery may occur in ten to thirty days, or the disease 

 may extend over weeks and months; it may make a cow dry and 

 produce atrophy or necrosis of the udder. 



The bacteria most commonly found in suppurative inflam- 

 mations of the udder are: Bacilli of the colon group, first called 

 Bacillus phlegmasia uberis by Kitt, now simply known as colon 

 bacillus. The organisms of this group have already been fully 

 described. Streptococci are frequently the cause of mastitis in cows, 

 but their presence in milk is by no means conclusive evidence of an 

 inflammation. In fact, some of the most common lactic-acid bacteria 

 in milk are of the non-pathogenic streptococcus type. Heinemann, 

 however, has succeeded, by repeated passages through the bodies of 

 rabbits, in changing non-pathogenic streptococci from milk into a 

 type pathogenic to rabbits in subcutaneous and intravenous injections. 

 This, however, proves nothing as to any original pathogenicity when 

 the organisms are taken into the stomach of man with milk. A large 

 number of observers have frequently found streptococci in market 

 milk, as for instance Bergey (Philadelphia, 50 per cent, of the samples), 

 Eastes (England, 72.5 per cent), Bruening (Leipzig, 93 per cent.), 

 Conn and Esten (Middle ton, 100 per cent.) and many others. Most 

 of the streptococci commonly found in milk belong to the type of 

 Streptococcus lacticus, one of the common lactic-acid formers in 

 milk, and these cannot by any known tests, except possibly occasionally 

 by animal inoculations, be distinguished from the Streptococcus pyo- 

 genes. If it is known that a cow has mastitis, then the streptococcus 

 present may be of the pathogenic, pyogenes type; but the disease 

 of the udder may also be due to bacilli of the colon group and the 

 streptococcus present be the non-pathogenic lacticus. The organism 

 known as Streptococcus mastitidis vaccarum forms both short and 



