cruzi will undergo development in tlie bed-bug and is infective 

 for ten days when injected into animals. S. cruzi will develop 

 not only in Ciine.t lectularius, but also in C. houeti and in 

 Ornithodoius monhata, which are all unable to transmit the 

 infection as does the true host of S. crvzi, a species of Conor- 

 rlvinus; (3) Swelling-rebel and Strickland's -pTOoiilmi Trypanosoma 

 lewisi will develop in the gut of C. lectularius ; the author has 

 himself confirmed these observations; (4) the author's own experi- 

 ments with bugs fed on rats infected with T. rhodesiense ; the gut 

 yielded trypanosome and crithidial forms and rounded parasites 

 seven days after feeding. 



Patton thinks that the parasite of Mediterranean infantile 

 kala azar will be found to flagellate in Cimex lectularius. The 

 author is of opinion that the same is true of the Leishinania of 

 canine kala azar and of the dermal leishmaniasis of South 

 America. 



The final stage of developTnent of Leishmania. 



Patton, in his last report on kala azar, lays great emphasis 

 on the appearance in the bugs of what he calls the post-flagellate 

 forms, which are rounded forms developed from the flagellate 

 forms. In the life-history of a typical Herpetomonas of any 

 insect such rounded forms are developed from the flagellates in 

 the hind gut, and it is these which, protected by some kind of 

 covering, pass out in the faeces, and are responsible for the trans- 

 mission of the infection to a new host. The round forms of 

 Leishmania found in bugs after the eighth day are compared by 

 Patton with the post-flagellate forms of a Herpetomonas, and he 

 is convinced that he has traced the whole development of the 

 Leishmania from the forms ingested through the flagellate stage 

 to the post-flagellate. In the bug, however, the post-flagellate 

 forms are not found in the hind gut but in the mid gut, and it is 

 supposed that they gain entrance to a new human host by regurgi- 

 tation when the bug bites. 



It is very difficult to decide whether the forms seen in the 

 bug are true post-flagellates in the same sense as those which 

 occur in insects. The author considers Patton' s reliance on a 

 staining reaction as misplaced, but the ultimate production of 

 round forms in the mid gut of the bug is evidence of the siini- 

 larity of behaviour of the Leishmania in the culture tube and in 

 the intestine. 



Patton has shown that the flagellate forms in the bug are 

 destroyed by a second feed of blood and attributes their absence 

 in mail to the effect of the blood and argues that the round post- 

 flagellate forms must be produced before infection can take place. 

 Artificial cultures of Leishmania may produce both Oriental sore 

 and kala azar when injected into animals. It must therefore 

 be some more resistant form in these cultures— a post-flagellate — 

 which causes the infection. 



The Development of Leishmania in the Bug is a very 

 restricted one. 

 Experiments with Oriental sore are much more difficult to 

 conduct than with kala azar. The author emphasi,ses the fact 



