240 Manual of Veterinary Microbiology . 



the respiratory passages of healthy individuals, or 

 are deposited on their food. Sputa or nasal discharge 

 may also be directly ingested by animals ; many in- 

 stances of the propagation of human tuberculosis to the 

 dog in this way have been recorded and it is probable 

 that in the stables a considerable number of cattle 

 contract the disease by consuming forage directly 

 soiled by the expectorations of their ngighbors. 



The milk of phthisical cows appears also to be an 

 important carrier of the germ; there is a difference 

 of opinion on the question whether or not the udder 

 can allow the passage of bacilli into the milk without 

 itself becoming invaded by the tubercular process; 

 some writers, basing themselves upon the result of 

 numerous tests, have come to the conclusion that this 

 does occur. However that may be, the difficulty of 

 deciding as to the non-existence of tubercles in the 

 mammar}^ glands furnishes a sufficient reason for ex- 

 cluding from consumption all milk to which such 

 suspicion is attached. Such milk is a dangerous food 

 for human beings and also constitutes a source of 

 infection for animals to which it is fed without pre- 

 vious cooking. 



The flesh of cattle affected with tuberculosis and 

 slauofhtered for the market also becomes virulent un- 

 der certain conditions but too little known. A cer- 

 tain number of inoculations which have been made 

 with muscle juice coming from such animals have 

 given positive results, although in the great majority 

 of cases the results of these inoculations have been 

 negative. Nevertheless the positive results obtained 

 are sufficient to establish the possible danger of the 

 flesh of X)htliisical cattle and to indicate the necessity 



