origin, and liumaai and bovine must be coiusidered as differ- 

 ent varieties with distinct charaoteristica. 



Possibly originally theee were the same, but long con- 

 tinued residence in one host have served to bring abouti 

 these differences. 



Formerly all ba.cilli found in man were considered 

 human type, but the Royal Co'mmiasion ha,ve clearly shown 

 that from 12 to 20% of lesions in the human body are caused 

 by organisms of the Bovine type. 



It is well known that tubercle bacilli can be excreted 

 with the milk from cows which show no physical eigns of 

 tuberculosis, and the same can only be demonstrated by 

 the Tuberculin test. And, beside this method, these bacilli 

 are also excreted with the feces, and may be conveyed to 

 the milk with other barnyard filth. 



Rutherford took a certain number of Reactors (with- 

 out manifest disease), and used the milk from these animals 

 in feeding hogs. At the end of one year 50% of these pigs 

 Vv'ere tuberculous. 



In the I'eport of the International Commission for the 

 Control of Bovine Tubcrculasis, we find the following con- 

 clusions regarding thp Tuberculin test: — 



"1. That Tuberculin, properly used, is an accurate and. 

 reliable diagiiostie agent for the detection of active tuber- 

 culosis. 



2. That Tuberculin may not produce a reaction Under 

 the following conditions : — 



(ai) When the disease is in a period of incubation. 

 (h) When the progress of the disease is^ arrested. ■ 

 (c) When the disease is extensively generalized. 

 The last condition is relatively rare and may usually 

 be detected by physical examination. 



3. On account of the period of incubation and the 

 fact that' arrested cases may sooner or later become active j 

 all exposed animals should be retested at intervals of six 

 months tot one year. 



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