ROLE OF STOMOXYS CALCITRANS. 



505 



Table XII. — Successive feeding of Stomoxys from infected to healthy 



animals." 



Inter- 







Inter- 







Inter- 







val 





Num- 



val 





Num- 



val 





Num- 1 

 ber of 

 flies ! 

 used. [ 



after 



Healthy 



ber of 



' after 



Healthy 



ber of 



after 



Healthy 



feeding: 



animal 



iiies 



feeding 



animal 



flies 



feeding- 



animal 



on in- 



used. 



ap- 



on in- 



used. 



ap- 



on m- 



used. 



fected 



monkey — 



plied. 



fected 





plied. 



fected 





animal. 







animal. 







animal. 







Days. 







Days. 







Days. 





1 



C 



87 



19 



J 



53 



37 



8 



14 



2 



D 



79 



20 



M 



49 



38 



9 



13 



8 



G 



90 



21 



N 



47 



39 



9 



12 



i 



L 



85 



22 







45 



40 



9 



9 



6 



M 



83 



23 



P 



43 



41 



11 



4 



6 



N 



81 



24 



s 



42 



42 



11 



2 



7 

 8 

 9 

 10 

 11 

 12 

 13 

 14 

 15 

 16 

 17 

 18 



P 



S 

 1 

 2 



3 

 4 

 8 

 9 

 10 

 11 

 C 

 G 



80 

 77 

 73 

 72 

 70 

 67 

 66 

 65 

 61 

 68 

 58 

 55 



25 

 26 

 27 

 28 

 29 

 30 

 31 

 82 

 33 

 34 

 35 

 36 



1 



2 

 2 

 2 

 3 

 3 

 3 

 4 

 4 

 4 

 8 

 8 



40 

 40 

 38 

 37 

 37 

 35 

 33 

 31 

 30 

 30 

 28 

 20 

















































































* Guinea pig A was used to feed the 90 flies of this series for three days prior to their 

 application upon the first healthy monkey. During the three days the blood of guinea pig 

 A was richly infected with trypanosomes. In emulsions made, 3 out of 4 flies examined showed 

 tremendous numbers of trypanosomes indistinguishable from those seen in the host's blood. 



INOCULATION OF FLIES FED ON INFECTED ANIMALS. 



To complete the discussion of the cyclical development of the 

 trypanosomes within the fly, it is necessary to refer to the length 

 of time flies remain infected after imbibing infective material. 

 Although, because of the uniformly negative results obtained in 

 many transmission experiments, this information remains of no 

 immediate practical value, it is included because the literature 

 on this subject is regarded as tending to mislead by magnifying 

 its importance. 



The length of time the infection is held in the insect certainly 

 is of prime significance where the infection is produced normally 

 through crushing of the intermediate host or through fascal 

 contamination. In both instances the transmission is consum- 

 mated by injection of the contaminative material into an abrasion 

 produced by the insect's mouth parts. 



