298 REPORT OF THE HARVARD AFRICAN EXPEDITION 
The histological picture, also, is not that usually observed in primary or 
secondary lesions of yaws, or in the primary lesions of syphilis. No spirochaetes 
were found in the tissues stained by Levaditi’s method. However, 1t is well 
recognized that spirochaetes are not usually found in the late lesions of either 
syphilis or framboesia, and Goodpasture ' was even unable to find spirochaetes 

No. 222. — Photomicrograph of downgrowth of epithelium, cellular infiltration, 
and condition of blood vessels (Case 385) 
in the histological study of the secondary lesions of yaws a short time after they 
had received treatment by the injection of neosalvarsan. 
We have already, in previous publications, described and compared the 
earlier lesions of yaws and syphilis. In syphilis, the primary lesion begins as a 
papule which, almost from the beginning, exhibits erosion of the surface epithe- 
lium, the underlying tissue becoming thickened and indurated, particularly on 
account of the great accumulation of cells in the skin and subcutaneous tissue. 
The Spirochaeta pallida infects primarily the epidermis. It is found chiefly 
between the epithelial cells in the epidermis, later affecting the lymph spaces and 
1 Goodpasture: Philippine Jour. of Sci. (1923), XXII, 263. 
