Two oriental strains of T. pallidum of Chinese origin were compared with two well known occidental strains, the Nichols and the Zinsser-Hopkins, on the basis of the clinical reaction to infection in the rabbit. Four experiments were carried out, two each in Peiping and New York. Animals from American and Chinese sources were represented in each experiment.
The results obtained showed that the reaction to both Chinese strains was generally comparable to that of the American strains. But with both Chinese strains, lesions of the eyes were more frequent, the time relations of certain phases of the reaction were shortened, and there was a higher incidence of complete recovery (latency) within the observation period. In view of the well known variability of the syphilitic reaction, however, it was not felt that these qualitative differences in clinical response could be ascribed to inherent or biologically fixed properties of the strains.