TUBERCULOSIS AMONG ANIMALS 



By W. A. BREND, M.A., M.B., B.Sc. 



The splendid work done by the Royal Commission on Human 

 and Bovine Tuberculosis, and the immense mass of observations 

 recorded in the six large volumes of the report and appendix, 

 afford material for research to independent investigators in 

 directions other than those taken by the Committee. One of 

 these is the problem of the curious and marked differences 

 in the degrees of susceptibility to tuberculosis exhibited by 

 the different classes of animals which were the subject of 

 experiment. 



The Commission was appointed to determine whether 

 tuberculosis in men and animals is one and the same disease, 

 and if, and under what conditions, transmission of it from 

 animals to men takes place. For the purposes of the inquiry 

 numerous experiments were made on dogs, cats, rabbits, rats, 

 mice, goats, pigs, bovines, monkeys, apes, and guinea-pigs. 

 Some of these animals were found to display remarkable 

 powers of resistance to the disease, others were susceptible 

 to extremely small doses of the virus. But though numerous 

 estimations of the degrees of susceptibility are made and 

 comparisons are drawn, nowhere, in either the report or 

 appendix, is any attempt made to suggest an explanation of 

 these differences. Nevertheless, when all the results scattered 

 through the volumes are collected and compared, an explanation 

 suggests itself which seems to accord fully with all the facts 

 observed. 



Let us begin by describing briefly what the results obtained 

 with different classes of animals were. 



It will be recalled that two separate and distinct investiga- 

 tions were carried on : one into the effects produced upon 

 animals by the bacillus of bovine tuberculosis, the other into 

 the effects produced by the bacillus of human tuberculosis. In 

 each series experiments were made both by injecting cultures 

 and emulsions of tuberculous lesions, and by feeding the 



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