VIII, B, 3 



Mitzmain: Transmission of Surra 



227 



HEREDITARY TRANSMISSION 



As a precautionary measure it was thought advisable to elim- 

 inate the possibility, however remote, of the existence of hered- 

 itary transmission of trypanosomes in these flies. 



In one experiment of this nature 74 flies were tested during 

 two weeks after the emergence of the lot by allowing them to 

 bite a healthy monkey. The eggs from which these flies de- 

 veloped had been laid August 14 by a fly which had fed twice 

 on a monkey infected with surra and whose blood was swarm- 

 ing with trypanosomes. The following table contains the data 

 resulting from allowing flies of this lot to feed on a healthy 

 monkey. Monkey 5, which was examined daily during the experi- 

 ment, showed no signs of infection and remained healthy until 

 April 12, 1913. 



Table II. — Experiments to test the hereditary transmission of surra infec- 

 tion in Tabanus on monkey 5; results negative. 



Date. 



Flies 

 tested. 



Average 

 time of 

 feeding. 



Nov. 5 



1 

 3 

 3 

 4 

 3 

 6 

 10 

 9 

 6 

 8 

 4 

 7 

 6 

 5 



Min. 

 4 

 7 

 7 

 9 

 6 

 6 

 9 

 10 

 8 

 6 

 7 

 6 

 4 

 4 



7 -... 



8 



9 . 



10 



12 



13 



14 - 



15 



16. 



17 



18 



19 



20— 





AN ATTEMPT TO TRANSMIT SURRA BY MEANS OTHER THAN BITING 



It was observed that many flies of both sexes in feeding sup- 

 plemented the sucking of the labium with the lapping of the 

 spongy labellum. Usually these processes are independent, but 

 not infrequently the female in attempting to bite the host will 

 lap up any moisture present preparatory to inserting its pro- 

 boscis. When an abraded surface is presented the majority 

 of flies of this species are capable of nearly filling the stomach 

 with blood without the aid of the proboscis. This has been 

 observed in numerous instances in flies used in biting experi- 



