88 MASTITIS OF THE COW 



the infection, bacilli again appear in the milk. That is to 

 say, the tubercle bacillus like the bacillus pyogenes is a 

 typical cell parasite. 



Udder-infection 



Udder-infection is not altogether infrequent. Figures 

 taken from statistics on tuberculosis in the Malmoer slaugh- 

 ter houses for 1905 showed ca. 3.5 per cent, of tuberculous 

 cows to be affected with udder-tuberculosis. 



The tubercle bacillus always presents a typical stroma- 

 infection which can, however, develop into a secondary milk- 

 infection by ulceration of the milk-canals. Stroma-infec- 

 tion is thus of the greatest importance. 



STROM A-iNFECTiON lluterstitial Mastitis] 



This infection has a typical chronic and progressive 

 character. 



Ports of Infection. — The infection can enter through 

 the teat canals, through wounds or through the blood. 



The infection through the blood is the most common. 

 It is one which follows tuberculosis of the lungs with blood- 

 infection following ulceration of veins. 



If a blood-infection is produced by any other organ 

 following ulceration of a vein or through transportation 

 by lymph through the thoracic duct, the infectious organ- 

 isms as a rule are picked up in the lung capillaries by the 

 leucocytes and carried into the lung tissue, by which process 

 the blood is freed from the organisms. It is, however, pos- 

 sible that one or more bacilli may not be carried into the 

 tissue of the lung, but pass through the lung and through 

 the pulmonary veins, ultimately reaching the blood of the 

 aorta and thus perhaps be carried to the udder. Thus it 

 is possible, although not frequent, that infection of the blood 

 of the udder is caused by tuberculosis in organs other than 



