EXPERIMENTS WITH INTESTINAL WullMS 3U[) 



large size of the eggs of the parasitic worms does not prechule 

 their dispersal by flies as experiments have indicated. 



Grassi (1883) appears to have been the first to demonstrate 

 the ability of flies to ingest the eggs. He broke up segments of 

 the common tape-worm {Taenia solium) in water; they had 

 previously been preserved in alcohol for some time. Flies sucked 

 up the eggs in the water and he found them unaltered in the 

 faeces of the flies. The eggs of T. solium measure, according to 

 NicoU (1911), '035 mm. in length and -025 mm. in breadth. Eggs 

 of Oxyuris were also passed unaltered. In another experiment 

 flies were allowed to feed on the eggs of Trichocephalus and 

 he found the eggs some hours afterwards in the flies' faeces 

 which had been deposited in the room beneath the laboratory; 

 he also caught flies in the kitchen with their intestines full of 

 eggs. 



Xuttall (1899) records a personal communication from Stiles 

 w'ho placed the larvae of Musca with female Ascaris lumhricoides 

 wdiich they devoured together with the eggs which these large 

 nematodes contained. The larvae and adult flies contained the eggs 

 of the Ascaris and as the weather at the time the experiment 

 was carried out was very hot the Ascaris eggs developed rapidly 

 and were found in different stages of development in the insect, 

 thus proving, as Nuttall points out, that M. domestica may serve 

 as a disseminator of this parasite. 



Callandruccio (1906) examined flies which had settled upon 

 faeces containing the ova of the tape-worm Hymenoleins nana and 

 the ova were found in the flies' intestines. Flies which had fed 

 upon material containing the eggs of H. nana deposited excrement 

 containing these eggs on sugar. Twenty-seven days later the 

 eggs of this tape-worm were found in the stools of a girl who had 

 eaten some of this sugar ; as other possible sources of infection 

 were carefully excluded this experiment clearly demonstrates a 

 method of infection by flies. 



Galli-Yalerio (1905) found that flies could carry not only the 

 eggs but also the larvae of the American hook-worm Necator 

 americanus. He was unable to find either eggs or larvae in the 

 intestines of the flies. Leon (1908) recovered the eggs of the 

 tape-worm Dibothriocephalus latus from the excrement of flies 



