Nc. G., DEPARTMENT OF AGRICULTURE. 47ti 



tainable from the post-mortem lecoi'ds of two of the largest hospitals 

 for children in this country have beco aual^zed with great care, iu 

 order to see what evidence they afforded as to the relative frequency 

 of the different methods of infection iu tuberculosis. In the case 

 of the Hospital for Sick Children in Great Ormond Street this has 

 been done by Dr. George Still, and in the case of the Koyal Hospital 

 for Sick Children in Edinburgh by Dr. Sheonan. The conclusion at 

 which Dr. Still arrived was that in 29.1 per cent, of the cases of tuber- 

 culosis in children, primarily infection appeared to have taken place 

 through the intestine. That is very far from being an insignificant 

 proportion, and it is a striking fact that Dr. Shenuan arrived at an 

 almost identical conclusion, and estimated that 28.1 per cent, of the 

 cases of tuberculosis amoug children in Edinburgh are due to alimen- 

 tary infection. There does not appear to be any ground for suppos- 

 ing that there is a large margin of error in these statistics, as the 

 number of cases dealt with was considerable (547 in the two series), 

 and in both series the post-mortem appearances were intrepreted 

 in a way to which no excejjtion can be taken. In face of these sta- 

 tistics it is not possible to assent to the statement that cases of 

 primary tuberculosis of the alimentary canal are extremely rare, 

 l^recisely the contrary conclusion is the one that must in the mean- 

 while be drawn with regard ta the state of affairs in this country, 

 viz., that, at least in children, primary infection by way of the alimen- 

 tary canal is comparatively common. 



I therefore submit that there is still a strong ijvima fade case 

 against animal tuberculosis as a possible source of human tubercu- 

 losis, and it becomes necessary to consider whether there are any 

 data from which one may estimate the extent of the danger to which 

 human beings are exposed through the occurrence of tubercle bacilli 

 in milk. 



The evidence in favor of the view that the ingestion of tuberculous 

 milk is one of the causes of human tuberculosis includes a num- 

 ber of recorded cases in which the relationship of cause and effect 

 appeared to be obvious. From the nature of the circumstances, evi- 

 dence of this kind is very scanty, and it must be admitted that very 

 few of the alleged examples are absolutely convincing. Tuberculo- 

 sis is a disease that develops slowly, and assuming for the moment 

 that tubercle bacilli do occur in milk, and are a cause of disease in 

 persons consuming such milk, it is obvious that, as a rule, the very 

 act by which the infection is brought about destroys the only direct 

 evidence of cause and effect that exists. 



One could only expect to be able to trace the disease to the milk 

 when, after the onset of symptoms pointing to infection by way of 

 the mouth, the cow from which the milk had been obtained was still 

 available for examination. In practice this is rarely the case, and 



