94 



At the time of starting these experiments nothing more 

 than the above was known of the life-histories of the three 

 species of Habronema found commonly in the stomach of the 

 horse. 



In attempting to determine the species of the larva found 

 in habronemic granulomata it became necessary to learn more 

 of the life-histories of the three species of Habronema. In 

 the latter part of 1916 experiments were started with this 

 end in view, and also to obtain material for animal experi- 

 mentation. The experiments had gone to show that under 

 artificial conditions both Habronema muscae and H. megas- 

 toma develop through their larval stages in Musca domestica. 

 At that time it was not possible to take the experiments any 

 further. 



Towards the end of 1917 the work was taken up again, 

 when it was found impossible to pass H. megastoma through 

 Stomoxys calcitrans. The work was proceeding when it was 

 learned that Hill, working at the Melbourne University Veter- 

 inary School, had confirmed the above findings, and had found, 

 further, that Habronema microstoma developed through its 

 larval stages in Stomoxys calcitrans and rarely in Musca 

 domestica, while Habronema muscae showed no development 

 in S. calcitrans. Nothing further of Hill's work has been 

 learned, and up to the time of writing (March, 1919) his 

 work has not been published. 



The experiments were continued during 1918 and the 

 early part of 1919. 



Method. — For the purpose of obtaining embryos, stomachs 

 taken from horses killed at the Zoological Gardens, Adelaide, 

 were examined. In all, considerably over one hundred 

 stomachs were examined. 



In the preliminary experiments carried out in 1916 

 stomach contents showing numerous embryos of Habronema 

 muscae, and in which no other species were found, were mixed 

 with horse-dung and exposed in the stables for about two 

 hours to allow flies to deposit their eggs thereon. The dung 

 used in the experiments was previously found to be free from 

 embryos capable of developing in Musca domestica. Dung 

 from the same animal was used in experiments with 

 Habronema megastoma, and the contents of the submucous 

 tumours were used to supply the embryos. 



In the later experiments sterilized dung was used, and 

 the embryos were obtained from the gravid female after 

 specific identification. In the case of experiments with 

 Habronema megastoma, embryos were also obtained by col- 

 lecting the contents of the submucous tumours after these had 

 been thoroughly scraped and washed in running water for 



