674 LEISHMANIOSIS 



a Romanowsky combination there was found to be a peripheral 

 portion coloured a pale blue and a central portion tending to be 

 unstained; there were also two chromatin bodies, one larger, 

 occupying a fourth or a third of the whole and situated in the 

 periphery, another smaller, round or rod-shaped, and of a deeper 

 colour than the larger mass. It was found that the bodies were 

 usually intracellular in position in the lesion, as many as twenty 

 being in one cell,. and that the type of cell containing them was, 

 as in kala-azar, that derivable from endothelial tissues. 



Wright's observations have been fully confirmed by workers 

 in various parts of the world, and it is now recognised that in 

 these tropical ulcers we have a third example of the activity of 

 a Leishmania. Various views have been held as to how infection 

 takes place, but Patton believes the bed-bug to be the inter- 

 mediate host perhaps exclusively during its nymph stage. The 

 incubation period before the sore develops is about two months, 

 and its duration is about a year. It is stated that after recovery 

 the individual possesses immunity. Sometimes the parasite is 

 destroyed in a foal ulcer, but it can be obtained by taking some 

 of the juice from the marginal indurated tissues by capillary 

 glass tubes. Patton reports having found the organism in the 

 blood taken from parts adjacent to the ulcer. Row has obtained 

 cultures in citrated blood, and Mcolle and Manceaux have re- 

 produced the condition in man, the monkey, and the dog, both 

 by virus obtained from the natural infection and from cultures 

 on Novy and MacNeal's medium. The lesions were identical 

 with those naturally occurring, but the incubation period was 

 often many months. It may be said that Thompson and Balfour 

 have described in the Soudan a condition in which subcutaneous 

 nodules without ulceration occurred in man, and these contained 

 Leishmania bodies. 



At present the tendency is to look upon the three Leishmaniae 

 as representing different species, but further investigation is here 

 necessary. It has been pointed out that in kala-azar, skin 

 ulcerations occur which might link this condition with tropical 

 ulcer, but it is to be noted that, while in the latter enormous 

 numbers of the parasite are found, in the ulcers of kala-azar, on 

 the other hand, parasites are difficult to find. Again, Nicolle 

 has found that dogs infected with Leishmania tropica appeared 

 to be not so susceptible to subsequent infection with Leishmania 

 infantum. These facts, however, might be consistent with the 

 existence of three species. 



Histoplasma capsulation. Under this name, Darling has described a 

 parasite observed by him in Panama in a case characterised during life 



