BY T. HARVEY JOHNSTON AND M. J. BANCROFT. 81 



proboscis was found to depend upon the rupture of some 

 portion of the organ, this apparently depending upon the 

 pressure exerted by the larvae, such pressure being 

 dependent on the number and activity of the worms present 

 (p. 103). He showed that under certain experimental 

 conditions, the larvae could set up granulomata in the 

 horse. 



In order to ascertain whether the worms could escape 

 from living flies we carried out some tests which were 

 suggested to us by observation of the habit of these flies, 

 especially 31. australis and M. vetustissima, in frequenting 

 the mouths and eyes of stock. 



Escape of Habronema from M. fergusoni. 

 A few M. fergusoni bred partly on cow dung and 

 partly on infected horse dung, and emerging from 18th 

 to 23rd May, 1919, were placed in a cage and fed on drops 

 ■of warm meat juice in a well-slide, the meat juice being 

 obtained by teasing up a small piece of raw beef in a little 

 water. The flies were also fed occasionally on honey and 

 water. 



On May 18th 4 flies present 

 On May 19th 4 flies present 

 On May 20th 7 flies present 

 On May 21st 5 flies present 

 On May 22nd 4 flies present 

 On May 23rd 5 flies present 



No Habro7iema escaped 

 No Habronema escaped 

 4 H. muscce escaped 

 \3 H. muscoE escaped 

 No Habronema escaped 

 No Habronema escaped 



On May 24th 5 flies present . . . . No Habronema escaped 



On May 26th 2 flies jirescnt . . . . No Hahroneina escaped 



On May 27th 2 flies present . . . . \ H. muscce escaped. 



One of the two surviving flies lived for three days, and 

 the other for seven days longer, but no more Habronema 

 escaped. On 22nd, 23rd, 24th and 25th Maj-, warm gravy 

 from cooked beef was used instead of raw meat juice. 



The total number of flies used in this experiment 

 was ( ight, while the total number of H. muscce escaping was 

 18. The escaping worms showed intense activity, as was 

 also the case in succeeding experiments where warm human 

 ■saliva was used instead of meat juice. 



Escape of Habronema from M. vetustissima. 

 Experiment I. — On November 2Cth, 1919, about 18 

 M. vetustissima bred on infected material were placed in a 



