428 



FAMILY: TRYPANOSOMIDiE 



cases of kala azar, and probably have a similar origin in the endothelial 

 lining of the vessels. The epidermis over the new tissue is often very 

 thin and degenerate, and in certain cases islets of epithelium are found 

 more deeply. In the ulcerating form the deeper tissue is composed of large 

 cells, but on the surface large numbers of pus cells are present also, and 

 the structure resembles that of an ordinary granulation tissue. 



MORPHOLOGY.— There is very little to add to the description given 

 above for L. donovani, a parasite which cannot be distinguished morpho- 

 logically from L. tropica. In any individual smear from a case of 

 oriental sore, however, the parasites appear to have a greater range of 

 form and size than they have in a smear from a case of kala-azar. The 



elongate, cigar-shaped forms are 

 more frequently encountered in 

 oriental sore, as also the larger 

 types of parasite (Fig. 192). They 

 occur in the cytoplasm of the large 

 macrophages, and their appear- 

 ance extracellularly in smears, as 

 in the case of L. donovani, is due 

 to rupture of cells in film-making. 

 In the ulcerating variety of sore, 

 wdiere there has been secondary 

 bacterial infection, and where pus 

 cells are abundant, there is a ten- 

 dency for degenerate parasites to 

 appear, and in various stages of 

 disintegration they may be found 

 in these cells. In such cases it 

 may be exceedingly difficult to 

 identify them, and when yeast-like 

 organisms are present also, con- 

 Yeasts often stain in a manner 

 closely resembling leishmania, and frequently exhibit a red area and a 

 deeply-staining granule. Rocha Lima (1912) drew attention to this 

 source of error, and pointed out that the organisms described by Darling 

 in Panama as Protozoa under the name of Histoplasma capsulation were 

 in reality yeast-like bodies from a case of blastomycosis. Yeasts, however, 

 have a much more distinct capsule, and the red area is more irregular in 

 shape than the nucleus of leishmania, while the deeply-staining dot does 

 not take on the characteristic rod-like form. Furthermore, reproduction 

 takes place by budding, and evidence of this can generally be found. 

 Another yeast-like organism, at one time considered to be a Protozoon 



Fig. 192. — Leishmania tropica from 

 Oriental Sore ( x ca. 5. ()(»()). (After 

 Wenyon, 1911.) 



1-3. Elongate torpedo- or cigar-shaped forms. 

 4-5. Abnormal forms in which kinetoplast alone 

 is visible. 

 6. More rounded form with dividing nucleus. 

 7-8. Appearance after fixation with Schaudinn's 

 fluid and staining with iron-hsematoxylin. 



fusion with these is easily made. 



