4S2 ANNUAL REPORT OF THE Off. Doc. 



to realize the seriousness of the dauger to which, in the present 

 state of affairs, those who drink uncooked milk are exposed. 



But there are one or two considerations that make the danger 

 greater than themere statement of the number of cows affected would 

 at first sight indicate. In the first place, the udder disease is not at- 

 tended by any pain or tenderness in milking, and the milk for a con- 

 siderable time after the udder has become manifestly diseased may 

 appear quite wholesome, though in reality it is charged with the 

 germs of tuberculosis. It therefore often happens that the gravity 

 of the condition is not realized by the milker or the owner of the cow, 

 and the milk continues to be sold for human consumption. There 

 is scarcely any room for doubt that if it were sold and consumed un- 

 mixed with other milk, some of the persons partaking of it would 

 become infected. In practice it is usualh' mixed with the milk from 

 other cows that have healthy udders, asid thus the germs are dis- 

 tributed among a larger number of persons. Even tuberculous 

 milk that has been thns much diluted may prove infective, but the 

 danger to the individual consumer is in inverse proportion to the 

 degree of dilution. 



Since about one cow in fifty is the subject of tuberculosis of the 

 udder, and the aA'erage number of cows in the milking herds of this 

 country is less thao fifty, it follows that the majority of dairies and 

 farms supply milk that is free from tubercle bacilli, or at least does 

 not contain any derived from this source. On the other hand, when 

 the infected malerial is present, it operates with the greatest inten- 

 sity in the milk of single cows, and in the mixed milk from small 

 herds. 



It must be added that tuberculous disease of the udder is not the 

 only source of tubercle bacilli found in milk. A great deal of the 

 milk in the market contains a considerable quantity of dust and dirt, 

 most of which comes from the cow's udder and the hands of the 

 milker, and part from the dust of the air of the cowshed. When 

 thirty per cent, of the cows in a b^re.are tuberculous, the dirt iu 

 that building, and the atmosphere in it, are almost certain to contain 

 tubercle bacilli, and some of these are very likely to find their way 

 into the milk. The more dirt milk contains, the greater is the chance 

 that tubercle bacilli from that source may be present. 



What has beeo said with regard to the extent of the danger to 

 which the public are exposed through the sale of milk containing 

 tubercle bacilli may be summed up as follows: — The danger cannot 

 be defined by stating how many persons are thus infected annually, 

 or what fraction the person thus infected form of the total number 

 who contract tuberculosis in the course of a year. At the same time, 

 it is impossible to doubt that the danger is a verv real one, since at 



