LEISHMANIA DONOVANI 411 



and divides, and at about the same time nuclear division commences. In 

 properly fixed material the nucleus is seen to elongate, while the spherical 

 karyosome at its centre elongates also, and is finally divided into two 

 parts, after which the entire nucleus becomes constricted at its equator, 

 and finally two result. Schulz (1924) maintains that the nucleus divides 

 by mitosis. Meanwhile, the new axoneme has continued its growth, and 

 a new flagellum is formed which gradually increases in length. Though 

 multiplication of the flagellum by longitudinal division has been described, 

 it is extremely doubtful if such a process ever occurs. After the new 

 flagellum has developed, splitting of the body, whether in the rounded 

 or elongated form, commences between the two flagella, and extends in a 

 posterior direction till two flagellates result. A characteristic feature 

 of the cultures is that the flagellates tend to remain clustered in groups, 

 with their flagella directed towards one another, so that rosettes or spheres 

 of organisms are formed with the flagella entangled at the centre. As the 

 cultures become old, elongate forms become less numerous, and many 

 rounded, non-flagellate bodies appear which resemble in many respects 

 the original leishmania. Many of these are, undoubtedly, degenerate or 

 dead forms, but the fact that subculture can often be obtained from 

 cultures of this type proves that some of them, at any rate, are living. 

 Cultures can be obtained from the spleen, as first shown by Rogers (1904), 

 or any other organ in which the parasites occur. They were cultivated 

 from the blood by Mayer and Werner (1914), and by the writer (1914), 

 while Shortt (1923c), and Shortt, Swaminath, and Sen (1923), have suc- 

 ceeded in growing them from the centrifuged deposit from the urine of 

 three cases of kala azar. 



Noguchi has found that L. donovani in culture can be differentiated 

 from other species of Leishmania by serological tests (p. 399). 



NATURAL INFECTIONS OF ANIMALS.— The only animals which have 

 been found naturally infected with L. donovani are dogs and cats, and the 

 latter only on one occasion, when Sergent Ed. and Et., Lombard, and 

 Quilichini (1912) published an account of a case of kala azar on a farm 

 near Algiers. The infected child was associated with a dog and a kitten 

 about four months old, both of which were infected. 



The dog has been frequently found infected, especially in the Mediter- 

 ranean region, and often in association with infected human beings. This 

 has given rise to the view of the canine origin of kala azar. 



The natural disease in dogs may run an acute or chronic course, and 

 the symptoms, as in man, are loss of weight, fever, anaemia, enlargement 

 of the liver and spleen. The dogs appear in bad condition, and are mangy 

 and often die of intercurrent infections. Recovery takes place more 

 frequently than in human beings. 



