442 MILK 



However, there is no reliable evidence to support this 

 assumption. Pathogenicity for experimental animals does not 

 presuppose pathogenicity for man. When mastitis milk is 

 injected into guinea-pigs it frequently causes lesions, but not 

 invariably. Puppel injected mastitis milk and a culture of mas- 

 titis streptococcus into the stomachs of guinea-pigs, but health, 

 temperature, appetite, and digestion remained undisturbed. Feed- 

 ing guinea-pigs with milk from ,a cow whose udder was caked with 

 mastitis produced no untoward effect. Lameris and Harrevelt 

 and Reed and Ward considered mastitis streptococci harmless to 

 guinea-pigs, although the latter authors were able to produce 

 mastitis in cows by .injecting mastitis streptococci into the udder. 



The studies of Davis and of Smith and Brown on the rela- 

 tion of mastitis streptococci to human sore throat have thrown 

 much light on the question. The latter authors injected guinea- 

 pigs with milk containing many leukocytes and with one sample 

 of milk containing streptococci. The guinea-pigs showed no dis- 

 ease and increased in weight. The authors also injected rabbits 

 with three hemolytic streptococci without results. They say, 

 "in searching for the particular streptococcus of an epidemic we 

 must search for an individual strain rather than a type." They 

 conclude that "the streptococci of cow mastitis are different from 

 streptococci of human tonsillitis; virulent streptococci of man do 

 not cause any appreciable inflammation of the cow's udder; mas- 

 titis streptococci do not cause affections in man; the udder of a 

 cow inoculated with virulent human streptococci may permit 

 certain strains to multiply in the milk ducts." In explanation of 

 the heightened virulence of the streptococci causing outbreaks of 

 septic sore throat the authors say, ."if bovine, they must repre- 

 sent a special strain rather uncommon, otherwise we should ex- 

 pect epidemics all the year round. If human, they may also 

 represent some peculiar type or else the product of a temporarily 

 increased virulence due to two co-operating factors, reduced viru- 

 lence on the part of human beings in the late winter and early 

 spring brought about by a combination of untoward living condi- 

 tions and better opportunity for rapid passage from throat to 

 throat a process tending to raise virulence in many micro- 

 organisms." 



It appears that epidemics of septitf sore throat may be dis- 

 seminated through milk-supplies, but the direct origin of the in- 

 fection is obscure in most cases. There is little doubt about the 

 fact that contact plays an important role in the transmission of 

 the disease. This was shown to be true in the Chicago epidemic, 

 and Winslow and Hubbard have emphasized the importance of 

 contact in their study of an outbreak of septic sore throat in New 



