284 BACTERIA 



may be desirable to state that the initial lesion, according 

 to Nocard and Bang, takes the form of a progressive scler- 

 osis. The interlobular connective tissue, normally scanty, 

 becomes thickened, fibrous, and infiltrated by minute mili- 

 ary granulations. The granular tissue is thus " smothered 

 by the hypertrophy and fibrous transformation of the inter- 

 stitial connective tissue " (Nocard). The walls of the ducts 

 are thickened and infiltrated, the lumen frequently dilated 

 by masses of yellow caseous material. On the whole it may 

 be said that tubercle of the udder is rare. Usually only 

 one quarter is attacked, and by preference the posterior. 

 For some time the milk remains normal, but gradually it 

 becomes serous and yellow, and contains coagula holding 

 numbers of bacilli. Lastly, it becomes purulent and dries 

 up altogether. While the milk is undergoing these changes 

 the lesion of the udder is becoming more marked, the tissue 

 becomes less supple, and the toughness increases almost to 

 a wooden hardness. 



The general anatomical characteristics of the disease are 

 similar to those occurring in man. 



The percentage of cattle suffering from tubercle varies. 

 In Germany it appears to vary from 2 to 8 per cent, of all 

 cattle, in Saxony 17 to 30 per cent., in England 22 per cent, 

 approximately (in London 40 per cent.), in France 25 per 

 cent. Lowland breeds are much more infected than moun- 

 tain breeds, which possess stronger constitutions. 



Tuberculosis of the//^ is less common than that of cattle, 

 but not so rare as that of the calf (Nocard). In nine out of 

 ten cases the pig is infected by ingestion, particularly when 

 fed on the refuse from dairies and cheese factories. The 

 disease follows the same course as in cattle. The finding of 

 the bacillus is difficult, and the only safe test is inoculation 

 (Woodhead). 



Sheep are very rarely tuberculous by nature, though there 

 is evidence to believe that very long cohabitation with 



