ROLE OF STOMOXYS CALCITRANS. 



495 



The latter is re- 



effects of the chloroform on a full stomach, 

 garded as the more plausible explanation. 



Button, Todd, and Hanington(34) write: "It was also found that flies 

 (Gl. palpalis) caught after they had fed on an infected animal, frequently 

 regurgitated a drop of blood as large as a pin's head, which was full of 

 parasites, many of them identical in form with those ingested. This was 

 observed up to twenty-eight hours after infection." The significance of 

 regurgitation as a means of transmission is noted. 



Koch<44) also found that, by pressure of the proboscis, trypanosomes 

 could be obtained from the labium of an infected Glossina. 



Table XV contains data of experiments concerning the point 

 under discussion. 





Table XV.- 



—Infectivity o 



/ dissected flies. 



No. of 

 ex- 

 peri- 

 ment. 



Time of completed or 

 interrupted feeding. 



Num- 

 ber of 

 flies 

 used. 



■ 



Interval 

 prior to 

 dissec- 

 tion of 

 flies. 



Guinea 

 pig re- 

 ceiving 

 probos- 

 cides. 



Guinea 

 pig re- 

 ceiving 

 abdo- 

 mens. 



Results of inoculation and fate 

 of guinea pigs. 









Minutes. 









1 



Interrupted i to 3 min- 

 utes. 



3 



1.5 



R 



U 



R negative. U positive tenth 

 day. 



2 



Complete, 5 minutes. ._ 



1 



0.5 



T 



S 



T positive twelfth day, dead 

 thirtieth day. S positive 

 twelfth day, dead thirty- 

 second day. 



8 



Complete, 40 seconds 

 to li minutes. 



5 



0.5 



103 



102 



103 positive ninth day. 102 

 negative. 



4 



Interrupted 30 seconds . 



6 



5.0 



121 



117 



121 negative, dead twenty-fifth 

 day. 117 negative, reacted 

 positive to inoculation of 

 subsequent experiment. 



6 



Complete, 1 to 7 min- 

 utes. 



5 



0.5 



113 



105 



113 positive tenth day. 105 

 negative. 



6 



Complete, 1 to 2l min- 

 utes. 



5 



5.0 



101 



28 



101 negative. 28 positive ninth 

 day, dead twenty-fourth day. 



Attempting to draw a deduction from the above data, it is 

 found that the surra organism remains in the proboscis for 

 thirty seconds, but disappears in one minute and thirty seconds 

 after the infective meal. The guinea pigs inoculated with the 

 abdominal contents of the flies serve as a control of the experi- 

 ments. The table demonstrates also that the proboscis of a fly 

 interrupted in its feeding, under the conditions stated, does not 

 appear to be infective. These experiments are by no means 

 conclusive. 



It was thought desirable to make an effort to ascertain whether 

 or not infection by direct transmission is due to any external 

 contamination. In other words, in what manner other than 



