TUBERCULOSIS OF THE COW 149 



proportion of human cases of bovine origin, until the accumu- 

 lation of further facts and the more precise differentiation of 

 the types of tubercle bacilli. Woodhead quotes Cobbett as 

 calculating from the data of the English Eoyal Commission, 

 that about 7 per cent of the cases with which we have to 

 deal are infected with bacilli of bovine origin. Woodhead 

 thinks this figure represents an under-statement. Whatever 

 the exact proportion, it cannot be regarded as other than a 

 serious menace to health. 



There is also a possibility which, if true, will make the 

 percentage of human tuberculous cases of bovine origin much 

 higher. The differences between the types of bacilli are differ- 

 ences of degree, and it is a possible supposition that bovine 

 bacilli ingested in early life may, under the influence of a 

 human environment, be extensively modified in type, and 

 ultimately approach the human type. The isolated bacilli 

 being then of human type, the infection will be ascribed to 

 a humaa source while really bovine in origin. There are 

 some facts in support of this hypothesis, but the whole 

 question must await the results of fuller investigations. 



In addition to the bacteriological evidence, statistics as to 

 the extensive prevalence of abdominal tuberculosis in children 

 furnish strong evidence that the path of infection is by in- 

 gestion in many of these cases. For example. Still, from 269 

 autopsies on tuberculous children under twelve years, came to 

 the conclusion that in 04 per cent infection was through the 

 lungs, and in 29 per cent through the alimentary canal. In 

 infants under one year, apparently only 13 per cent contracted 

 tuberculosis through the intestine. Shennan, dealing with the 

 autopsies at the Eoyal Hospital for Sick Children in Edin- 

 burgh, put the percentage of cases infected through the 

 alimentary canal at 28'1. Woodhead found that out of 127 

 cases of tuberculosis in children, in 100 tuberculosis of the 

 mesenteric glands was present, while in 43 there was ulceration 

 of the intestine. 



The following tables given by Dr. J. Thomson ^ show that 

 abdominal tuberculosis is a condition which is prevalent to a 

 considerable extent amongst children in Great Britain. 



' British Journal nf Tuberculosis. 1907, vol. i. p. 250. 



