ROLE OF STOMOXYS CALCITRANS. 

 Table XVI. — Feeding the progeny of infected flies. 



509 



Date. 



Num- 

 ber of 

 flies 

 ap- 

 plied. 



Total length 



of time flies 



were fed. 



No. of animal 



used. 







Hours, tnina. 







Mar. 21, 1912 



7 



86 



Guinea pig 68. 





Mar. 22, 1912 



8 



41 



Do. 





Mar. 23, 1912 



7 



36 



Do. 





Mar. 24, 1912 



15 



1 1 



Do. 





Mar. 25, 1912 



19 



1 29 



Do. 





Mar. 26. 1912 



22 



1 37 



Do. 





Mar. 27. 1912 



23 



1 49 



Do. 





Mar. 28, 1912 



25 



1 56 



Do. 





Mar. 29, 1912 



25 



2 3 



Do. 





The result of this experiment with guinea pig 68 was negative. 

 This animal has been used since for surra inoculation to which 

 it reacted positively August 4, 1912. 



A second experiment of this type was carried out with the 

 progeny of flies fed on a surra horse. The horse was kept 

 in a fly-screened stall for six days during which time flies were 

 permitted to feed undisturbed. Several hundreds of the flies 

 were removed from the stall and placed in a jar with horse 

 manure. Seventeen days later new flies emerged, 75 of which 

 were selected for feeding on a guinea pig. The flies were fed 

 daily for eight days when the animal was kept under observation 

 for forty-five days, after which time the experiment was judged 

 to be negative. 



Surra organisms have never been encountered microscopically 

 in numerous lots of eggs laid by infected flies nor in emulsions of 

 larvse developing from eggs deposited by surra-fed adults. 



On May 9, 1912, this was tested in a more convincing way by 

 inoculating material of this sort. With laboratory-bred flies as 

 the parents, 30 larvae, the progeny of 13 flies which had been 

 fed several days on a surra monkey, were emulsified in salt 

 solution and then inoculated into 2 guinea pigs, 97 and 98. This 

 also gave a negative result. 



The experiments of the next series, in which attempts were 

 made to transmit the surra trypanosomes through the larvae, 

 are obviously grossly mechanical, although the principle involved 

 in hereditary transmission as set forth by Calkins (58) is readily 

 recognized as also mechanical in the sense of inheritance by 

 contact. 



