LEISHMANIA TROPICA 435. 



exposed surfaces of the body more commonly than any other part. Whatever may 

 be said in favour of the bed bug being a possible vector of L. donovani, no sound 

 arguments, epidemiological or other, can be adduced in support of the claim that it 

 is the cause of oriental sore. 



Patton (1922) stated that he has been able to obtain a development of L. tropica 

 in the bed bug similar to that obtained by Adie with L. donovani (see p. 419). 

 Presumably, intracellular stages were seen, but as these occurred in the cells of 

 the gut only after its removal from the body and incubation at a suitable 

 temperature, they can hardly be recognized as representing a normal process of 

 development, and still less as proving conclusively that the bed bug is the true host 

 of L. twjyica in Cambay in India, as Patton maintains. No host can be regarded as 

 being conclusively incriminated in the transmission of L. tropica or any other 

 parasite till the infection has been actually transmitted by it. 



Fleas. — Working with fleas {Pulex irritans and Ctenocephalus cants), which the 

 writer (1912c) fed on an oriental sore resulting from his inoculation in Aleppo, no 

 evidence of development of L. tropica could be obtained. In these experiments the 

 fleas were attached to wire according to Noller's method, and before feeding on the 

 sore were proved, by examination of the fseces ejected during feeding, to be free 

 from flagellate infection. When fed on the sore, it was noted that leishmania were 

 ejected with the faeces even in the first portion passed, proving that the fleas had 

 actually ingested parasites. The fleas were then incubated at 22° C, the optimum 

 temperature for culture. They were fed from time to time on the wrist, but no 

 evidence of flagellates which might have developed from the leishmania could be 

 found in the ejected faeces. Fleas found naturally infected with leptomonas con- 

 stantly passed flagellates in the faeces. The fleas which had given negative results 

 for leishmania were then fed on a rat harbouring Trypanosoma lewisi, and afterwards 

 on the wrist as before. On the sixth day infective forms appeared, and continued in 

 the faeces, thus proving that the conditions of the experiment were suitable for the 

 development of a natural flagellate of fleas. 



Laveran (1917) describes attempts to transmit L. tropica from mouse to mouse by 

 means of fleas. Four healthy mice, together with others heavily infected with 

 L. tropica, were placed in a glass jar which was serving as a flea breeding-place. There 

 were so many fleas present that the mice had eventually to be removed for fear 

 of their being killed by continued abstraction of blood. Three of the mice were 

 examined after five months, and the fourth after eight months, but no infection had 

 taken place. 



Lice. — Patton could obtain no evidence of the development of L. tropica in lice. 



Mosquitoes. — The writer (1911a), working in Bagdad, fed thirty-one Culex 

 fatigans on oriental sore. It had been proved by dissection immediately after 

 feeding that mosquitoes readily took up leishmania from a sore of the non-idcerating 

 variety. The mosquitoes dissected twenty-four, forty-eight, and seventy-two hours 

 after feeding showed no trace of flagellates. In a few out of a large number of JEdes 

 argenteus {Stegomyia fasc lata) which had fed daily on the sore, rounded bodies possibly 

 derived from the leishmania were found on dissection twenty-four or forty-eight 

 hours after feeding. An attempt at transmission by means of twenty-six of these 

 mosquitoes which had fed repeatedly on the sore and then on the arm gave no result. 



Phlebotomus. — The writer (1911 ) first recorded the existence of a natural Lepto- 

 moitds of the sand fly in Aleppo, an endemic centre of oriental sore. W^hat is 

 probably the same flagellate has been found in P. papatasi in Palestine by Adler 

 and Theodor (1925a). It is possible that the flagellate was actually Leishmania 

 tropica. Mackie ( 1 914b) then gave the name Herpetomonas 2)hlebotomi to a flagellate 



