124 ANNUAL REPORT OF THE Off. Doc. 



subject by way of the digestive had. Koch called attention (o the 

 fact that when tuberculosis is carried from cattle to mankind, it is 

 through the food and especially through the milk, for meat is 

 usually conked enough to destroy tubercle bacilli, if any should be 

 present. This being the case, he concluded that when coming from 

 cattle, the disease should originate in the victim as a primary intes- 

 tinal tuberculosis. Koch seems to have had the opinion that in cases 

 of food infection, the only, or at any rate the chief, lesions should 

 involve the intestines. He calls attention to the reports of the 

 Charite' Hospital in Berlin showing that, in a great mass of material 

 but ten cases of primary tuberculosis of the intestines occurred in 

 five years, and also that among 033 cases of tuberculosis in children 

 Baginsky never found tuberculosis of the intestines without simulta- 

 neous disease of the lungs and the bronchial glands. 



With reference to this point, it may be said that the cases ad- 

 mitted as primary intestinal tuberculosis under Koch's very rigid 

 interpretation of this term, do not furnish any evidence whatever 

 as to the frequency with which infection occurs through the digestive 

 tract. It has been shown that tubercle bacilli may pass through 

 the wall of the intestines and enter the blood system by way of the 

 thoracic duct without causing any visible alteration in the intestinal 

 wall. Indeed, when animals are artificially infected with tubercu- 

 losis by feeding them tuberculous material, it is very rare to find 

 ulceration of the intestine, or tubercles in the walls of the intestines, 

 unless an excessive quantity of infectious material has been fed. 



It has happened in some carefully conducted experiments that 

 animals infected by feeding have, after death, shown extensive 

 tuberculosis of the lungs and very little disease, indeed sometimes 

 no trace of disease, in the organs of the abdominal cavity. 



A third point made by Koch in the address referred to, is stated 

 in these words: "Hitherto, nobody could decide with certainty in 

 such a case whether tuberculosis of the intestine was of human or 

 of bovine origin. Now we can diagnose them. All that is necessary 

 is to cultivate in pure culture the tubercle bacilli found in the 

 tubercular material, and to ascertain whether they belong to bovine 

 tuberculosis by inoculating cattle with them." In this view, Koch 

 is in accord with Smith, who holds that the type of the bovine 

 tubercle bacillus is so fixed that it is not lost through growing in the 

 human subject, so that after the death of such subject, the germ 

 may still be recognized as of bovine origin, and the surest test for 

 this is to determine whether it is capable of producing disease in a 

 calf. 



Since 1001, a very great amount of fruitful study by leading bac- 

 teriologists has been devoted to this particular problem. The State 

 Livestock Sanitary Board has always held a leading position in 

 these investigations. It is clearly established that tubercle bacilli 

 as they occur in mammals may be divided into two varieties or types; 

 the bovine type, which grows slowly in artificial cultures, which 

 is relatively thick and short and which is highly virulent for rabbits, 

 cattle and all other mammals; and the human type, which grows 

 more readily in artificial cultures, is slightly longer, more slender, 

 is more inclined to be beaded and which is but slightly virulent for 

 rabbits and cattle and is of lower virulence than the tubercle 



