20 Gerald F. Hill : 



hoAvever, motionless. At noon on the following day (December 8th> 

 the remaining eight tlies were examined, three of which harboured 

 12 larvae. Of these nine were dead and three succumbed a few 

 hours later in saline solution. Thus the longest period of survival 

 was about two days, tlius confirming Ransom's observations (1913, 

 p. 14). 



G, To determine the possibility of -escape of larval Habronema 

 nuiscae from Hies. 



On many occasions living flies were placed in moistened Petri 

 dishes Mith tlie object of determining whether, under such condi- 

 tions, tlie parasites could escape eitlier before or after the death or 

 tlie flies. In no instance could larvae be found in the dishes, 

 although from subsequent exaaninations it was proved that the fiies'- 

 were heavily infected. 



Similar negative results were obtained in experiment's in which 

 infected flies Avere allowed to die and remain foi- periods up to two- 

 days in saline solution. 



Development. 



The eggs and developing embryos, as found in tlie gravid female, 

 are shown in Fig. 1. The egg (Fig. la) measures from 0.04 mm., 

 to 0.05 mm. in length by 0.01 mm. to 0.013 mm. in breadtli. Pro- 

 gressive stages of development are shown in Fig. 1, b, c, d, e, and 

 f, in all of which the embryo is enclosed in a thin elastic sheath or 

 egg-shell. In tlie stages shown in Fig. 1, e and f, two or three 

 nuclei are usually seen, the largest being about 0.033 mm. to 0.036 

 mm. from the anterior end, the others at distances varying from 

 0.015 mm. to 0.035 mm. from the posterior end. A clear space- 

 surrounding what appears to be the rudimentary pharynx is rarely,, 

 though very indistinctly, seen. What appears to l>e a horn-like- 

 process at tlie anterior end can be made out with difficulty in the- 

 stage shown in Fig. 1, f. 



The dimensions of the specimens figured are as follows : — (a) 0.043' 

 mm. long by 0.013 mm. wide, (b) 0.052 mm. long by 0.0132 mm. 

 wide, (c) 0.053 mm. long by 0.018 mm. wide, (d) 0.069 mm. long by 

 0.009 mm. wade, (e) 0.075 mm. long by 0.007 mm. wide, with 

 nucleus at 0.033 mm. from the anterior end. In d. e, and f, the 

 measurements given are of the embryo only, exclusive of the envelop- 

 ing sheath, which varies in shape and size with the movements of 

 the embryo, and no allowance is made for the bent tail end. 



As Ransom has stated (1913, p. 16) the embryos undoubtedly pass 

 out of the body of the liorse: in the faeces. Fij?; 2 shows an embrvo' 



