[Bacteriology of leprosy].

In a previous communication (2) a description of an acid-fast organism isolated from human and rat leprous lesions was reported! Embryonic chick tissue-cultures were used as the isolation medium. Later reports (3,4,5) have dealt with the influence of various environmental factors on the tinctorial characteristics of the organisms that were isolated. The present communication deals with results obtained in work done at the United States Marine Hospital, Carville, Louisiana. The same media as reported in the first paper of the series were employed, namely, embryonic chick tissue cultures, minced chick embryo medium, and glycerin veal agar slants. In addition, the above methods were paralleled by the procedure recommended by McKinley and Soule (1), employing glycerin veal agar slants kept under a gaseous environment of 40 percent oxygen, 10 percent carbon dioxide and 50 percent nitrogen. The purpose of the work was to determine whether or not the same organism could be isolated repeatedly by the method outlined in the first report of this series. A satisfactory experimental animal for human leprosy is not available, but if the same organism can be isolated repeatedly in pure culture, that may be indirect evidence that the cultured form is the true etiological agent of leprosy. There is considerable doubt in the minds of many workers that a satisfactory experimental animal would determine whether or not the isolated organism is the true agent of the disease. It is known that if rat granuloma is kept in the laboratory for several weeks and then injected into young normal rats, it is unable to produce rat leprosy. In other words, the material must be injected into new