TUBERCULOSIS AND THE MILK SUPPLY 223 



repeated an interesting study of such a streptococcus present in 

 the healthy udder of a cow from 1897 to 1900. After death the 

 glandular tissue of the udder was also examined, with the result 

 that abundant quantities of streptococcus, possessing some degree 

 of virulence, were found in the substance of the gland. It was 

 not possible to differentiate this organism from streptococci derived 

 from udders with marked mammitis, set up by infection or by 

 some slight local irritation. It is probable that streptococci exist 

 in the healthy udder much more frequently than is generally sup- 

 posed, and on this account it is possible that its effect upon persons 

 consuming the milk is slight or nil, for if it were otherwise more 

 illness might be expected to follow milk consumption. Bergey 

 found that of 40 samples of rharket milk 36 (or 90 per cent.) 

 yielded micrococci, and 20 (or 50 per cent) yielded streptococci. 

 Streptococci were found somewhat more frequently in the milk of 

 cows kept under insanitary conditions, but the difference was not 

 ver}' marked.^ Bergey agrees with Beck, who repeated a number 

 of experiments in 1900, that it is most probable that these organ- 

 isms are not infrequently the cause of serious gastro-intestinal 

 disorders in infants, and probably far more frequently than is 

 generally supposed. 



We may now consider in some detail a typical disease of 

 man contracted through the channel of the milk supply, and 

 reserve to a subsequent chapter a consideration of epidemic 

 infective diseases so transmitted. The type is tuberculosis, and 

 we propose to make reference to it only as bearing upon its 

 relationship to the milk supply. 



Tuberculosis and the Milk Supply 



We have selected tuberculosis as a type of disease intimately 

 related to milk for two simple rea.sons. Its bacteriology and 

 pathology are more fully worked out than that of any other disease 

 related to milk, and it is a disease the agents of which may gain 

 entrance to the milk from either the bovine or human side. It is, 

 moreover, a disease which is claiming a large amount of study and 

 consideration at the present juncture, on account of the many and 

 wide practical issues raised by the new knowledge acquired respect- 

 ing it during the last twenty years. 



The specificity of tuberculosis.— There is now a large body of 

 evidence which goes to prove that tuberculosis is one and the same 

 ^ American Medicine, 1901, 20th April, p. 122. 



