FEEDING INTESTINAL WORMS TO I-'LIES 315 



200 eggs were recovered from faeces of other flies. 171 eggs were 

 recovered from a fly 24 hours after feeding ; these eggs were fed 

 to a rabbit in which 23 Cysticerci were afterwards found, showing 

 that the eggs remained capable of infecting for at least one day. 

 Eggs were also recovered from a fly and fV(^]ii faeces 48 hours 

 after feeding. 



7. 10 Hies were fed on faeces containing ruptured mature 

 segments ; a piece of sugar was also introduced and the faeces 

 were kept moist. The results demonstrated the important fact 

 that faeces containing tape-worm segments may continue to be a 

 source of infection from which food, such as sugar, may be con- 

 taminated for as long as a fortnight. 



A series of experiments was carried out in which fly larvae 

 were fed upon faeces containing tape-worms or ripe segments. 



Taenia serrata. 5 eggs were recovered from three larvae two 

 days after they had been placed on dog faeces containing ripe 

 segments but no eggs were recovered from pupae or flies developing 

 from larvae which had been fed on infected faeces. 



Toxascaris limhata. Larvae were placed on dog faeces con- 

 taining mature female worms but no embryos or larval tape-worms 

 were recovered from the fly larvae, pupae or adult flies. 



Ascaris megalocephala. Several larvae were put in horse 

 faeces containing female worms with numerous eggs. Negative 

 results were obtained from an examination of the fly larvae, pupae 

 and adult flies. Nicoll points out that these results are at variance 

 with the result of Stiles already quoted, but, as he shows, the eggs 

 of Ascaris lumhricoides, which Stiles used, are smaller than those 

 of ^. megalocephala. 



XicoU also experimentally shows that the well-known habit 

 which flies have of cleaning their proboscides, appendages and 

 bodies after feeding militates very materially against their carry- 

 ing eggs on the exterior of their bodies. The longest period after 

 which eggs of Hymenolepis diminuta, for example, were found 

 adhering to flies was about three hours. During this time, how- 

 ever, they may travel some distance from the source of infection. 

 It was demonstrated that the eggs of this species of tape-worm, 



