The so-called "protozoan-like" cells with which this paper is concerned were first described in 1904 by Jesionek and Kiolemenoglou,1 who found them in the kidneys, lungs and liver of an eight months fetus, in intimate association with lesions of hereditary syphilis. The authors pictured these extraordinary structures as measuring on an average from 20 to 30 microns in diameter, usually oval in outline, possessing a well defined, though not sharply stained, cuticular zone having the appearance of a capsule. The nuclei were large, eccentrically placed, each containing a very pronounced "central nuclear body" surrounded by two well defined zones, an inner dark and an outer clear zone. The entire nucleus appeared separated from the cell body by a membrane. In the clear outer zone of the nucleus were found spherical, darkly staining granules of different sizes averaging 1 micron. The width of the nucleus, inclusive of the membrane, measured