HUMAN DISEASES 545 



The question arises whether the spread of infection may be 

 expected to be followed by its own antidote in the form of a gradual 

 increase of resistance against the disease. There is some hope that 

 this resistance may be developed, but the general conclusion is 

 that the African appears to be relatively deficient in the power 

 to develop against our European tubercle bacillus the localizing 

 barriers of cellular tissue and fibrosis which work for spontaneous 

 cure in persons of European stock (Lyle Cummins 1935). The 

 excessive incidence and death rate among the negro population of 

 the United States, as compared with the whites, may also suggest a 

 biological dissimilarity in the average response to infection between 

 the black and white races. Against this, however, it may be pointed 

 out that the Red Indians of North America do take on, after a 

 certain number of years, the same reaction to infection as white 

 people, and there are now, in Canada, tribes enjoying almost the 

 same resistance as the whites. It is possible that the negroes of 

 the United States of America and even of Africa would similarly 

 develop resistance if they came to have the same living conditions 

 as the white races. This latter view is supported by experience in 

 the Belgian Congo, where the Government has made efforts to 

 stop the spread of tuberculosis by methods of isolation. By a law 

 on the loth October 1931, it was ruled that every non-native 

 person suffering from tuberculosis of either kind must leave the 

 country, and that every native patient must be isolated in a hos- 

 pital. Experience, especially of the FOREAMI doctors, is that the 

 latter measure has had most beneficial effects and that individual 

 resistance is increasing. 



Research on tuberculosis among the native population in Uganda 

 carried out by Dr. Carmichael, the assistant veterinary patholo- 

 gist, has shown that most infections are with the human and not 

 with the bovine type of bacillus (Uganda 1935, D.R.). 



Since 1 9 1 3 valuable work has proceeded in Algeria and Morocco, 

 the Cameroons, Senegal, and the Congo. In particular, inquiries 

 into tuberculin sensitivity, etc., initiated in the French African 

 colonies in 191 2 by Professor Calmette, constitute a great body of 

 knowledge which has continued to bear fruit ever since. In spite 

 of these researches, however, tuberculosis in the towns of French 

 West Africa is said to be increasing. Prophylactic treatment, 



