262 REPORT OF THE HARVARD AFRICAN EXPEDITION 
withdrawn in four of our cases also remained sterile, and no micro-organisms of 
any nature could be detected on microscopical examination. In only one case, 
No. 498 (excluded from this series), were onchocercal embryos and adult para- 
sites demonstrated. 
The number of leucocytes in the serum of fluid removed from the other 
juxta-articular tumors varied greatly. In one case there were very large numbers 
of polymorphonuclear leucocytes, but no bacteria were present. Large, greatly 
swollen endothelial cells containing phagocytized cells and nuclei were observed 
in four of the cases. Tissues from the different cases were hardened in Zenker’s 
solution and in formalin and stained by Levaditi’s silver impregnation method, 
Giemsa’s stain, Ziehl-Neelsen’s method, carbolfuchsin, and methylene blue, and 
eosin and haematoxylin and eosin and Vierhoff’s stain. 
Histological study of the sections of the juxta-articular nodules removed from 
our cases show in general near the center of the nodule, a necrotic area or areas 
in which there are many polymorphonuclear leucocytes, phagocytes and, es- 
pecially, large swollen cells resembling foam or lipoid cells, often containing large 
numbers of phagocytized cells or chromatin particles. There are also in some 
areas the usual endothelial cells and a few small round cells. In these necrotic 
areas, no bacteria or parasites are visible. Outside such areas of more acute 
inflammation, which almost resemble abscesses save for the absence of purulent 
exudate, is a zone in which round cells, plasma cells, and fibroblasts are usually 
visible in varying numbers. Still further toward the periphery the nodule is 
composed of very dense fibrous tissue in which no elastic fibers are observed. 
The skin over the tumors is practically normal in appearance. We have not 
been able to demonstrate any definite spirochaetes in the sections stained by 
Levaditi’s method or by Giemsa’s solution and no acid-fast bacilli were found in 
sections stained by the Ziehl-Neelsen method. A better idea of the complete 
histological picture can be obtained from a review of the examination (with 
illustrations) of one of the cases (Case 75, Nos. 194, 198, and 199). The 
epidermis and upper layers of the corium are not pathologically changed, with 
the exception that the corneal layer is somewhat thickened. The peripheral 
zone of the nodule consists of very dense fibrous connective tissue in which there 
are very few vessels. This tissue is generally not rich in nuclei, but as one ap- 
proaches the center, one finds areas in which the fibroblasts are proliferating and 
the nuclei more numerous. In other areas nearer the center of the nodule the 
connective tissue is richly vascularized. The vessel walls are slightly thickened 
and there is evidence of early endarteritis and peri-arteritis, the proliferating 
endothelial cells extending in places into the surrounding tissue. Some of the 
blood vessels show all coats of the arteries moderately thickened. 
As one approaches still nearer to the center of the lesion, one finds the con- 
nective tissue fibers pushed apart, and there are spaces in which large numbers 
of polymorphonuclear and endothelial leucocytes are present. In other areas 
there are yellow masses or clumps of altered blood pigment. Finally, in the 
center, one finds large areas of necrosis with openings in the fibrous tissue occu- 
pied only by polymorphonuclear leucocytes and by swollen vesicular, foam-like 
