ROLE OF STOMOXYS CALCITRANS. 



489 



Flies bred in the laboratory were used in this series, and they 

 were discarded after each experiment. The interval of time 

 between feeding on an infected animal and a healthy animal 

 is stated in the table as the approximate average per fly. The 

 flies were not fed individually, but from a common bottle into 

 which the monkey's tail was introduced. (Plate III.) 



Table V. — Mechanical transmission by interrupted feeding of Stomoxys on 



monkeys. 



No. 

 of 

 ex- 

 peri- 

 ment. 



1 

 2 

 3 

 4 

 6 

 6 

 7 

 8 

 9 

 10 

 11 

 12 

 13 

 14 



Infect- 

 ed mon- 

 key 

 used. 



Number of trypa- 



nosomes 



found. 



Healthy 



monkey 



used. 



Num- 

 ber of 

 flies 

 used 

 on in- 

 fected 

 mon- 

 key. 



Length 



of time 



flies 



were 



applied 



on 

 infect- 

 ed mon- 

 key. 



Interval 

 between 

 feedings, 

 approx- 

 imate 

 average 

 per fly. 



Flies 

 feed- 

 ing 

 at 

 time 



of 

 trans- 

 fer. 



Number 

 of flies 

 fed on 

 healthy 

 mon- 

 key. 



Length of 

 time fed 



on healthy 

 monkey. 



F 

 R 

 R 

 F 

 F 

 F 

 F 

 F 

 F 

 F 

 F 

 F 

 F 

 F 



Scanty 



D 

 C 



S 

 M 

 P 

 B 

 L 

 H 

 J 

 N 

 20 

 20 

 2S 

 2M 



9 



15 



22 



5 



19 



6 



9 



12 



12 



2 



9 



9 



18 



1 



Minutes. 

 18 



4 

 15 



2 

 53 



5 

 20 



6 

 20 



3 

 18 

 12 

 35 



2 



Minutes. 

 2 

 1 

 3 

 2 



2i 

 2 

 3 

 2 

 2 

 2 

 2 



2i 

 3 

 3 



4 

 15 

 11 

 4 

 7 

 5 

 2 

 6 

 5 

 2 

 4 

 7 



15 

 1 



9 



15 

 22 

 15 

 19 

 5 

 9 

 4 

 12 

 2 

 9 

 9 

 18 

 1 



Minutes. 

 20 

 15 

 20 

 13 

 60 

 20 

 24 

 18 

 30 



7 

 20 

 60 

 60 



3 





Numerous 



Moderate 



Numerous 



do 



Numerous 



Swarming 



Numerous 



do - - 



Swarming 



do 



do 





The negative results of this series are checked in one ex- 

 periment by the inoculation of surra blood from an infected 

 bullock into the tail of monkey B. The animal reacted first 

 on June 10, 1912, and died on June 22, 1912. 



The relatively long interval between feedings is accounted 

 for by the fact that much time was consumed in manipulating 

 the tails of the respective monkeys, in forcibly interrupting the 

 biting of the flies, and the renewed processes on the second host. 



In Table VI, 11 experiments with an equal number of guinea 

 pigs are represented. Here the flies were more easily controlled 

 in the element of time, and, for purposes of close observation, 

 each fly was fed from an individual test tube. The time was 

 accurately noted with respect to three considerations; namely, 

 feeding on the surra host, the interval interrupting the feeding 

 during the transfer, and the completion of the meal on the healthy 



