30 Arsenphenylglycin and T. gambiense in G. palpalis. 



the available positive boxes, so that each monkey had every chance of 

 infection. In many cases boxes had to be ignored owing to their proving 

 negative on dissection. Each monkey was kept under observation for a 

 considerable time in consideration of the enormous incubation period 

 reported in certain experiments by Mesnil and Kerandel where trypanosomes 

 appeared only after 39 days. No such phenomenon occurred here. 



Thus a dose of arsenphenylglycin of - l grm. per kilogramme will protect 

 a monkey against infection by positive G. palpalis if given within 12 days 

 before exposure. 



Expt. 

 No. 



Period elapsing 



between the 

 administration 

 of the arsenic 



and the 

 application of 

 the positive 

 flies. 



Number of 

 experiments fed on 

 monkey. 



Number of posi- 

 tive flies to which 

 monkey was 

 exposed. 



Duration 

 of 



examina- 

 tion of 

 monkey. 



Eesult. 



Eemarks. 



First tested 

 on a clean 

 monkey and 

 proved infec- 

 tive. 



Not 

 so 

 tested. 



1st day. 



2nd day. 





hours. 

















720 



72— 96 



2 





4 



4 



56 







719 



96—120 





3 



10 



10 



61 







724 



120—144 



2 



1 



5 



5 



50 







774 



144—168 





4 



4 



4 



65 







775 



144—168 





4 



4 



3 



65 







749 



168—192 



2 



2 



8 



5 





+ 



Incubation period 



















10 or 11 days. 



748 



192—216 



1 



2 



4 



1 





+ 



i> » 



Thus a dose of arsenphenylglycin of O05 grm. per kilogramme will protect 

 a monkey from infection by positive G. palpalis if given within seven days 

 of exposure. Using the inoculation method of infection, Mesnil and 

 Kerandel proved that 0'05 grm. of this drug per kilogramme was capable 

 of protecting a monkey from infection up to within three days of the 

 administration of the drug. 



Conclusions. 



I. By feeding a G. palpalis which is infective with T. gambiense on an 

 animal whose blood contains arsenic administered within 24 to 48 hours, 

 the gut flagellates in the fly may be destroyed. Those of the salivary 

 glands, however, which are the infectiDg forms, are unaffected. It is highly 

 probable that the gut may become repopulated with flagellates from the 

 salivary glands. 



II. Preliminary feeding of flies on arsenic-containing blood has a deterrent 



