290 REPORT OF THE HARVARD AFRICAN EXPEDITION 
stages of the condition, — the nodular, caseous, ulcerative, healing, and cicatriz- 
ing, — were represented. 
The tissues from these lesions were placed in Zenker’s solution or formalin 
immediately after their removal and were later sectioned and stained in hae- 
matoxylin and eosin, Giemsa’s solution, by the Ziehl-Neelsen-Gabbett method 
for acid-fast bacilli, by Levaditi’s silver impregnation method, and in a few in- 
stances by Weigert’s stain. 
The histological appearance in some of the cases varies considerably. 
However, in general, in the vicinity of the ulcerative lesions the condition is 
characterized by the presence of granulation tissue in which there are some 
areas richly cellular and others where proliferation of the fibrous tissue is marked, 
but usually with few, if any, giant cells. The inflammatory process is usually of 
rather a diffuse character and not sharply limited in nodular form. The cellu- 
lar exudate is composed particularly of plasma cells, endothelial cells, fibro- 
blasts, polymorphonuclear leucocytes and small round cells. In a few instances, 
nodular areas were observed in the corium and subcutaneous tissues, in the 
center of which coagulation necrosis has sometimes occurred. Around the 
central areas the tissue is characterized by the presence of proliferating fibro- 
blasts and numerous round cells. This zone in turn is surrounded by an area 
of granulation tissue which is richly vascular and contains many round cells, 
endothelial cells, plasma cells, and a few polymorphonuclear leucocytes. Eosino- 
phils are not prevalent or noticeably increased in number in the tissues. The 
vessel walls show in some areas moderate endarteritis and thickening of the 
walls and evidence of periarteritis with the proliferating endothelial cells ex- 
tending into the surrounding tissue. However, marked evidences of extensive 
endarteritis and thickening of the vessel walls is not present. Rather surpris- 
ing is the slight tendency in the ulcerative lesions to the secondary invasion of 
the tissues by spirochaetes and fusiform bacilli and by cocci, as is seen, for 
example, in phagedenic ulcer. Spirochaetes were not found in the corium in any 
of the many sections studied. Acid-fast bacilli were also especially sought but 
were not found. 
In Case 222, a Liberian albino negress (Nos. 212-213), large numbers of Blas- 
tomyces were found in the necrotic ulcerative lesion on the left leg, but only 
near the surface of the lesion. These Blastomyces were not present in the deeper 
portions of the tissue. In this patient, in addition to the numerous ulcerative 
lesions and extensive scarring of the skin, there was distinct thickening of 
the periosteum of the anterior surface of the tibiae. The photomicrograph 
(Illust. No. 214) illustrates the cellular infiltration, as well as the character 
of the granulation tissue showing numbers of newly-formed blood vessels in 
the corium and with no apparent pathological change in the walls of the larger 
vessels. 
In No. 215 (Case 405), is illustrated the characteristic central area of coagu- 
lation necrosis sometimes observed in the subcutaneous tissues and already 
referred to. In this case, the tissue was removed from near the edge of the 
ulcer with a portion of the apparently normal overlying skin. The ulcer was 
