TR YPA NO SOMIDjE 



I. It behaves like L. donovani in that it does not readily infect dogs 

 experimentally. 



II. It behaves like L. donovani in that it produces a local cutaneous 

 lesion, with or without a general infection, when inoculated into 

 the skin of a monkey. 



He further believes that it is a special variety of L. donovani 

 because: — 



I. It has signs of a coccal stage in its life-history. This has been 

 objected to by Wenyon and Laveran, but has been confirmed by 

 Smallman in two cases from Malta and by Stathan and Butler in 

 Sierra Leone. 



II. Experimental evidence is not in favour of its being insect-borne. 

 On the contrary, careful feeding experiments suggest that the 

 method of infection is oral, while a study of the epidemiology and 

 other facts make it probable that it is water-borne. The feeding 

 experiments have been confirmed by Basile, though objected to by 

 Laveran, while the epidemiology supports facts noticed by Bous- 

 field, Thomson, and Marshall. 

 III. The local lesion produced by intracutaneous inoculations into 

 monkeys does not exhibit any eosinophile leucoc3^tes, which is 

 different from the lesions produced by L. tropica, but it is not 

 known whether this occurs or not in those due to L. donovani and 

 L. infantum. 



We therefore recognize it as L. donovani varietas archibaldi. 



Leishmania donovani Laveran and Mesnil, 1903. 



Definition. — Leishmania, producing in man the signs and symp- 

 toms of tropical kala-azar, in experimental monkeys general and 

 local infections, but not readily infecting dogs. 



History. — The history is fully given in Chapter XLVU., p. 1289, 

 and it need only be remarked that the parasite discovered by Leish- 

 man in 1900 was described by himself and by Donovan in 1903; 

 while Rogers, in 1904, cultivated the parasite at 22° C. and discovered 

 the flagellate stage. 



Christophers, in 1904, considerably added to our knowledge of 

 these parasites, and Patton, in 1906 and 1907, showed that they were 

 not merely found more commonly in the leucocytes of the peripheral 

 blood than had been previously believed, but that they could develop 

 into typical flagellates in the bed-bug, Clinocoris rotundatus Signoret, 

 1852 (which is the same as C. macro cephalus Fieb), but this is 

 apparently more in the form of a natural culture than of a cyclic 

 development. 



Development in the Bug. — According to Patton, the parasites are ingested 

 by the bug enclosed in the large cells or leucocytes, as just mentioned, and 

 develop into fully flagellated forms without reference to the temperature of 

 the external air. 



. The first change begins usually by an increase in size up to 4 to 7 and a 

 vacuolation of the cytoplasm on the second day, but may be deferred for 

 several days. 



The single parasite may proceed directly to flagellation by the appearance 

 of an area stained bright pink by Giemsa, and called ' the flagellar vacuole.' 

 This vacuole, which has a dark centre, rapidly increases in size up to i to 3 

 and, passing to the surface, sends out a small pink brush, which forms the 

 flagellum by merely growing longer. There appears to be no doubt that the 



