BOVINE TUBERCULOSIS 65 



The Royal Commission did not conclude that the 

 human and the bovine types represent two distinct organ- 

 isms, but preferred to regard these two types as varieties 

 of the same bacillus, and the lesions which they produce, 

 whether in man or in other mammals, as manifestations 

 of the same disease. Dr. Arthur Eastwood, the bacterio- 

 logist to the Commission, after mention of the remark- 

 ably stable characters of the viruses, says: ' I find that 

 underlying all the mammalian viruses which I have 

 investigated there is an essential unity of characteristics, 

 the differences observed being differences of degree but 

 not of kind. On artificial culture media they all grow 

 in the same way, though they differ quantitatively in 

 the amount of growth yielded. In the tissues of suitable 

 experimental animals they all produce lesions histologically 

 characteristic of mammalian tuberculosis, though they 

 differ in the intensity of the tissue changes which they set 

 up under similar experimental conditions.' As the 

 Commission have conclusively shown that many cases 

 of fatal tuberculosis in the human subject have been 

 produced by the bacillus known to cause the disease 

 in cattle, they are emphatic that the possibility of such 

 infection cannot be denied. Of fifty-nine cases of tuber- 

 culosis in pigs investigated by the Commission fifty yielded 

 the bovine virus, three the human, five the avian, and 

 one a mixture of the bovine and avian. 



Butter, skimmed milk, and butter-milk will contain 

 tubercle bacilli if made from tuberculous milk. The use 

 of the mixed milk of a herd, although perhaps reducing 

 the risk, does not entirely remove it. Desirable though 

 it would be to prohibit the use of meat from animals 

 suffering from any manifestation of tuberculosis, economic 

 considerations have to be regarded. It is found that 

 the fat and muscular tissues are seldom involved, the 

 lungs, liver, and pleura (' grapes ') being the organs most 

 often diseased. The Royal Commission on Tuberculosis 

 (1898) recognised the fact that tubercle bacilli are seldom 

 encountered away from diseased areas, and recommended 

 that, provided the carcasses b^ otherwise healthy, in the 

 restriction of lesions to the lungs, thoracic lymphatic 

 glands, liver or pharyngeal lymphatic glands, the non- 

 tubercular portions of the carcass should not be con- 

 demned. 



5 



