798 



THE LEISHMANIOSES 



The parasites are almost always intra-cellular, generally in large endothelial 

 cells, sometimes in leucocytes, and occasionally in the red cells of the blood. 

 A large number of parasites are often found in one cell and as many as 50 to 

 200 have been found within a rounded amorphous mass of tissue representing 

 probably a disintegrated cell. 



Ti, 



FIG. 384. Leishmania donovani. (After Guiart.) a, Leishmania in a macro - 

 phage ; b, c, d, parasites in the spleen ; e, longitudinal division ; f, multipart* - 

 tion ; g, h, i, j, cultivation forms. 



Leishmania donovani occurs as a small rounded or oval organism measuring 

 2-4/x in diameter. When stained by Romanowsky's or Leishman's stain it 

 is found to possess a large spherical poorly-staining nucleus, and a short 

 rod-shaped deeply-staining blepharoplast arranged perpendicularly or tan- 

 gentially to the nucleus ; occasionally a prolongation in the form of a tail i& 

 seen, attached perpendicularly to the blepharoplast ; this probably repre- 

 sents the remains of a flagellum (fig. 384 d). Reproduction is generally by 



simple longitudinal division (fig. 384 e), 

 occasionally by multiple fission in which 

 case the mother-parasites are larger and 

 I spherical and show several chromatin 



masses arranged in couples (nucleus and 



blepharoplast) around which the protoplasm 

 segments (fig. 384 f). 



't [Sections. For the recognition of the 



parasite in sections of tissues the follow- 

 *f ing methods are recommended (Nattan- 



i| Larrier). 



- 



FIG. 385. Leishmania donovani. x 1000. 

 Smear from spleen from a case of Kala 

 Azar (Leishman's stain). 



Fixation. Any of the following fixatives 

 are good provided* the pieces of tissue be small. 

 (8X4X3 mm.) 



(i) Acid perchloride. 



(ii) Saturated aqueous solution of per- 

 chloride. 



(iii) Alcohol. Leave the tissue in 70 per 

 cent, alcohol for 3 hours, then in 80 per cent, for 3 hours and finally in 90 per cent, 



vl malin * The tissue ma y be Pl ace d in 2 per cent, formalin for 3 hours 

 and then passed through alcohol as above. 



Embed in paraffin. 



Staining. The best results are obtained with the following procedures : 



(i) Carbol-thionin. Stain for 30 min. Wash in distilled water. Dehydrate 

 rapidly in absolute alcohol. Differentiate in oil of cloves and afterwards in absolute 

 alcohol. Clear in xylol. The nuclei are shown very prominently. 



(11) Kernschwarz and carbol-thionin. Stain in Kernschwarz for 15 min. Wash 

 well in distilled water. Stain in carbol-thionin as above (i). 



