That the causative organism of abortive disease in cattle may be pathogenic for man was suggested by Larson and Sedgwick1 in 1913. Evidence substantiating this possibility was furnished by Alice Evans2 in 1918, when she showed that Brucella abortus and Brucella melitensis are so closely related that it is impossible to differentiate them except by the agglutinin absorption test. The actual proof of this close relationship was submitted by Carpenter3 in 1926; he reported two cases in which he had isolated Brucella abortus from the patients' blood and from the cow's milk consumed by the patients. Later he produced abortion in pregnant heifers by inoculating them with the organism recovered from the patient.
In view of the fact that abortive disease in cattle is widespread in this country, the possibility of human infection has existed for a long time. It therefore became of interest to consider from