:\-l Gerald F. Hill: 



and sixteen adult Hies from January 10th to 16th, all of Avhich were- 

 infected, the number of larval nematodes in each varying between 

 4 and 50, averaging about 25. 



Experiment No. 13. 



After a period of forty-eight hours' incul)ation at room tempera- 

 ture, a culture of previously sterilized faeces containing embryos 

 from twenty specimens of Habronema microstoma was infected oni 

 January 16th, with nine-d_ay-old larvae of Musca domestica, and 

 with Stomoxys calcitrans larvae of the same age. Tlie majority 

 of the Musca larvae and some of the Stomoxys had already ceased 

 feeding, consequently infection of the former was not expected. 

 Only two Musca domestica flies emerged (January 27th and 28th), 

 neither of which harboured nematode larvae. On the other hand, 

 two Stomoxys larvae which were examined on January 2th, har- 

 boured four and five parasites respectively, Avhile each of three 

 pupa examined on January 23rd and 20th contained upwards of 

 thirty-five parasites. Other Stomoxys pupae were examined be- 

 tween these dates, each of which was heavily infected. 



Experiment No. IJf. 



Embryos from six worms were liberated in sterilized faeces on 

 January 22nd, and incubated at room temperature until January 

 29th, when Musca domestica larvae, then five days old, were added 

 to the culture. Twenty-three flies emerged on February 11th and 

 12th, of which number one only was infected. This parasite (Fig, 

 26) was evidently malformed. 



B. To determine the frequency of larval Habronema in Stomoxys 

 calcitrans, and their abundance and location in the body 

 of the intermediate host. 



(i.) Free or Cauglit Flies. — During tlie period May to November 

 63 flies, 10 pupae and 12 larvae of Stomoxys calcitrans were col- 

 lected in the Institute grounds and examined for the presence of 

 Habronema. Of this number only one fly was found to be infected 

 (May 4th). The parasite, which was located in the abdomen, 

 measured about 1.5 mm. in length and agreed with typical examples 

 of larvae of H. microstoma, as found in flies bred and infected in 

 the laboratory. 



(ii.) Laboratory bred flies sliowed a very high percentage of 

 infection, avS will be seen by reference to Experiments No. 10, page- 



