The Complete Life-history of the Organism of Syphilis.

THE sporozoite when examined in vivo remains for some time unstained, but later stains very deeply without its motility becoming thereby impaired. It is seen in two forms-(a) circular, (b) renalshaped-its size is about 11 microns in diameter, and it is actively motile; occasionally I have seen distinct flagelle attached to it. Besides being found in the scrapings from syphilitic lesions, it can be found in the blood withdrawn from the healthy skin surrounding a chancre and also in the general blood-stream during the stage of general infection. I have found it in the former when I was unable to find the Spirochatta pcallida in the scraping from the sore; therefore the sporozoite is of great diagnostic importance. The sporozoite then becomes intracellular. On two occasions I have seen it in a small mononuclear leucocyte: it remained actively motile while within and ultimately left the cell. The cell it makes its host is a connective tissue cell, and when inside it undergoes important changes, which can best be described under two headings (1) The sporozoite steadily increases in size, and by a process of budding gives rise to several bodies which later become differentiated into male and female elements. By this time the cell is a sac, as all the reserve material has been used up by the mierozoites, but the nucleus still remains although degenerated, and then it finally disappears when the sac gives way and frees the male and female merozoites. Not all the bodies formed in this way are sexually differentiated; there are others which become free with the sexual merozoites and are able to start the cycle again by seeking a fresh connective tissue cell.