^0 Gerald F. Hill : 



D. To detenniiie the period of survival of larvae removed from 

 flies. 



At 4. p.m. on December 21st, six of the encysted H. megastoma 

 larvae referred to under Experiment 19, page 47, were placed in 

 sterilized normal saline, contained in a covered Petri dish. All 

 Avere living on the following afternoon, three died before 10 a.m. 

 of the next morning, December 23rd (forty-two hours), two died 

 before 10.30 a.m. on the next day (December 24th), and the last 

 "died before 4.30 on that afternoon, a maximum of four days. 

 These parasites were in the stage of development shown in Fig. 45. 



On December 24th (noon), eleven larval H.« megastoma, from 

 Experiment No. 20, page 48, Avere treated as above. Four died 

 before noon on December 26th (two days), four before noon on 

 December 27th, and the remaining three before noon on December 

 28th (maxinmm of four days). These parasites were about 1.6 mm. 

 long, and therefore probably in the stage of development shown in 

 Pig. 46. 



These experiments are, of course, quite insufficient to give any 

 positive evidence, but in each case the larvae would appear to live 

 much longei- than do those of H. muscae and H. microstoma under 

 .■similar conditions, suggesting a much greater resistance on the 

 part of the H. megastoma embryos than that of the other species. 



E. To determine the period of survival of larval H. megastoma 

 in dead flies. 

 Three flits from Experiment No. 20, page 48, which 

 ■emerged on the afternoon of December 23rd, were killed in a 

 cyanide of potassium killing-bottle on the morning of Decem,ber 

 24th, and placed on moist filter paper in a covered dish. One fly 

 Avas dissected late in the afternoon, and found to contain two living 

 parasites. The others were examined early on Decen)ber 26th, 

 ^vhen one only was found to be infected, the two parasites which 

 ^vere contained in the abdomen being dead. 



4.— Development. 



The eggs and young embryos of Habronema megastoma, as found 

 in the uterus of the gravid worm, are illustrated in Fig. 36. The 

 e^^ (Fig. 36a) measures from 0.04 mm. to 0.05 nmi. h)ng by about 

 0.01 mm. wide, and is similar to that of H. muscae. Later stages 

 in development are shown in Fig. 36b, and c, which measured 

 0.05 mm. long by 0.013 mm. wide, and 0.053 mm. long by 0.015 



