Tuberculosis in Its Relation to the Dairying hidustry. 751 



counti'ies and reports furnished periodically by the various inspectors 

 point to certain types as being more predisposed to this disease 

 than are other breeds, and this, as previously stated, I attribute to 

 the heavy strain imposed in producing large (juantities of milk. As 

 it has been fairly pro^^en that while the disease is rarely transmitted 

 hereditarily, there is a marked predisposition that the progeny of a 

 tubercular animal will later on develop the same complaint as the 

 dam. 



Etiology or Cause of Disease. 



It has been demonstrated by Koch that this disease is due to the 

 presence in the tissues of the body of the tubercle bacillus, but the con- 

 ditions under which the tubercle was transmitted to the animal may vary. 

 Perhaps it is by means of the coughed up tubercular matter from an 

 affected animal which has been deposited on the grass which is eaten 

 by another animal, or may be by animals licking each other as stated 

 by Bang. Comet, Colli, and other investigators, state it is hardly 

 possible that it has been exhaled into the air by one animal and in- 

 haled by another in a pure condition. In animals shedded or stalled 

 in byres, it is evident as will be shown later on that one affected 

 animal may infect all others in the same shed by the coughed up 

 sputum drying, and being blown over the food which the other 

 animals are eating. Or again, anyone supplying milk to a creamery 

 who was milking an animal affected with tuberculosis, and selling it 

 with the milk of other cows, is disseminating the disease broadcast 

 among not only his own but his neighbours' calves and pigs, which 

 feed on a mixture of such milk, this the more so if the disease exists 

 in the udder of the animal, although the milk may produce similar 

 results from the animal so affected even though the udder is not the 

 seat of disease. ' Various continental investigators have proved 

 that dairy produce (whey, cheese and butter) from animals suffering 

 with this disease may cause it to be transmitted even after a lapse of 

 as much as four weeks. Bang affirms that he has proved that milk 

 which has been skimmed by a separator loses a lot of its tubercule 

 bacilli through their being driven into the sediment. This process 

 does not afford absolute protection, as skimmed milk and cream so 

 prepared hav^e been found on inoculation capable of setting up tuber- 

 culosis. Milk does not in every case afford positive results micro- 

 scopically of the presence of the spore or bacillus of tuberculosis, 

 yet by inoculation with it the disease has been set up in other 

 animals. Bollenger, from the milk of 20 affected cows, was able to 

 detect its presence in one sample by the aid of the microscope, 

 although by inoculation experiments he introduced it in 11 cases, and 

 the researches of many others have been attended with similar results. 



Having thus seen how readily bovine tuberculosis may be trans- 

 mitted among cattle, and we are aware that tuberculosis claims each 

 year such a number of human victims, I hope I may not be considered 

 empirical in bringing under notice the opinions of many eminent 

 scientists of the relationship which exist between the bacilli of the 

 disease in man and other animals. When Dr. Robert Koch first 



