Kala-Azar 



are concerned. Any associated growing bacteria quickly destroy 

 Leishmania donovani. 



Under conditions of cultivation the appearance of the organism 

 undergoes a complete change. It enlarges, the nucleus increases 

 greatly in size, and a pink vacuole appears near the blepharoplast. 

 In the course of twenty-four to forty-eight hours the organism 

 elongates, the blepharoplast moves to one end, and from the vacuole 

 near it a flagellum is developed, and the organism becomes in about 

 ninety-six hours a flagellate protozoan resembling herpetomonas. 

 It now measures about 20 ^ in length and 3 to 4 /z in breadth, its 

 whip or flagellum measuring about 3 ju additional. It is also motile, 

 and, like the trypanosomes, swims with the flagellum anteriorly. 

 There is no undulating membrane. 



This may be regarded as the perfect or adult form of the organ- 

 ism. It multiplies by a peculiar mode of division first observed by 



Fig. 218. Leishmania donovani. Flagellated forms obtained in pure cultures 



(Leishman). 



Leishman. Chromatin granules, a larger and a smaller, appear 

 in the protoplasm in pairs, after which, through unequal longitudinal 

 cleavage, long, slender, almost hair-like individuals, containing one 

 of the pairs of chromatin granules, are separated. These were 

 serpentine at first, but later, as they grew larger, a flagellum was 

 thrust out at one end. 



Distribution. The Leishman-Donovan body is widely distrib- 

 uted throughout the body of the patients suffering from kala-azar. 

 It occurs in great numbers in the cells of the spleen, of the liver, of 

 the bone-marrow, and in the ulcerations of the mucous membranes 

 and skin. In the peripheral blood they are few and only in the leuko- 

 cytes. They are always intracellular, or when in the circulating 

 blood may be found in indefinite albuminous masses, probably de- 

 stroyed cells. The number in a cell varies up to several hundred, 

 such great aggregations only being found in the peculiar large cells 

 of the spleen. 



Lesions. The splenomegaly is the most striking lesion. The 

 change by which the enlargement is effected is not specific. The 



