374 



Col. Sir D. Bruce and others. [Apr. 18, 



somes found in laboratory-bred flies may therefore be considered to be derived 

 from the infected animal they had fed upon. 



Table III. — Development of Trypanosoma gambiense in Laboratory-Bred 



Glossina palpalis. 



Experiment. 



No. of flies. 



-iNO. 01 



days fed on. 



JNo. or days beiore 

 flies became infective. 



No. Oi days liies 

 remained infective. 



725 



8 



3 



— 



— 



733 



8 



3 



— 



— 



750 



15 



6 



— 



— 



768 



9 



5 



— 



— 



858 



9 



8 



— 



— 



915 



6 



10 



— 



— 



947 



9 



5 



— 



— 



975 



16 



5 



34 



49 



991 



27 



6 



— 



— 



1266 



11 



12 



— 



— 



1269 



22 



7 



— 



— 



1368 



14 



12 



— 



— 



1397 



7 



19 





— 



1428 



50 



6 







1431 



30 



20 



— 



— 



1452 



90 



10 



— 



— 



1549 



50 



4 



37 



46 



1558 



60 



4 



— 



— 



1559 



50 



4 



— 



— 



1566 



35 



4 



53 



53 



1602 



50 



4 



27 



27 



1604 



35 



12 



— 



— 



1640 



40 



10 



— 



— 



1651 



60 



4 



41 



41 



1664 



50 



12 







iDUO 



o\) 



1 9 







1671 



45 



12 







1672 



28 



12 







1680 



45 



4 







1686 



60 



3 







1688 



60 



3 







1693 



50 



4 







1700 



60 



7 







1712 



50 



12 



32 



32 



1758 



50 



3 







1760 



60 



4 



29 



29 



1761 



50 



4 



38 



38 



1769 



60 



3 







1801 



70 



12 







1802 



76 



12 







]8f;0 



60 



12 







1868 



60 



12 







T 



Among these 42 oxperiin(;iit.s tliorc were only eight positive, while there are 

 as many as 34 negative. In the eight positive experiments, 371 flies were 

 used, an average of 46 ; in the 34 negative experiments, 1323 flies, an 

 average of 40. The shortest i'mn\ which elapsed before a laboratory-bred fly 



