394 SANITARY ENTOMOLOGY 



named bug and Brumpt has proven it a durable host. Brumpt has also 

 demonstrated development in the bedbugs Cimcx lectularius, C. boueti, 

 and C. hemipterus. 



There are two types of reproduction of the organism in the insects. 

 In the sexual method, about six hours after ingestion of blood the kineto- 

 nucleus moves close to the trophonucleus with which it possibly blends ; 

 the flagellum and undulating membrane are now usually lost, but some 

 forms retain the flagellum. The parasite becomes rounded and multiplies 

 repeatedly by division. After this has ceased it becomes pear-shaped, 

 develops a flagellum and becomes a crithidial form and then passes into 

 the cylindrical portion of the intestine where it can be seen in about ^5 

 hours after the ingestion of blood. The final stage is a small, trypaniform 

 type, long and slim with band-like trophonucleus and large kinetonucleus. 

 This form is found in the hind gut in the body cavity and in the salivary 

 glands, and is the form by which the parasite is transmitted to a new ver- 

 tebrate host. The development in the bug requires at least eight days 

 for its completion. 



The asexual method of reproduction is a constant process and is a 

 simple multiplication, giving rise to the crithidial forms which are found 

 principally in the hind gut. 



Originall}' the disease was supposed to be transmitted by the sucking 

 of blood by insects. Brumpt declares that transmission is exclusively 

 by dejections. As Rhodnius proUxus passes its dejections immediately 

 after removing its beak, while the Triatoma species do not pass dejection^ 

 during their repast, Brumpt thinks it likely that Rhodnius is a more 

 potent transmitter, in view of the fact that dejections are infective. In 

 this connection the bedbug has a very interesting habit which bears upon 

 the possibility of its transmitting the disease. Patton and Cragg have 

 pointed out that it defecates immediately after a feed, but unlike the 

 majority of bloodsucking insects, does not pass out red blood, but only 

 the remains of the last meal, a semi-solid sticky material. This black 

 fluid is passed out just after the proboscis is M'ithdrawn, and the bug 

 has a very characteristic habit of turning around and moving back- 

 wards in such a way that the excreta fall in the ncighborliood of the 

 wound made b\' the proboscis. Blacklock has studied the multiplication 

 and infectivity of S. cruzi in Cimex lectularius, and concludes that the 

 organism is capable of living and multiplying in the bedbug for long 

 periods. The parasites found in the bedbug are infective on inoculation 

 as early as 21 hours and as late as 77 days from the infecting feed. 

 Transmission of the disease to healthy animals by feeding an infected 

 bug on them is of very rare occurrence. It was only once observed in the 

 course of these experiments. In the light of Brumpt's work, we can now 

 see that feeding experiments were almost naturally to be expected not to 



