236 JOHN E. GUTBERLET 



host in some cases. Furtherwore, feeding chicks on flies that were 

 taken from about the chicken roosts and raising the cestodes make 

 it probable that the house-flies are the intermediate hosts of this 

 one species. 



The reason why more flies were not infected by feeding on 

 the eggs of this species was determined to be peculiar conditions in 

 the maturing of the proglottid. At the time when the experiments 

 were being carried on it was not known that the oldest proglottids 

 separated from the worm before they are entirely mature. In the 

 experiments the oldest proglottids on the worm were usually taken 

 for feeding, though in some cases the free segments in the intestine 

 were used. Since the flies were fed on eggs that were not entire- 

 ly mature the embryos were digested. The free proglottids remain 

 in the intestine of the bird for some time and in all probability 

 mature there. Some such free proglottids were examined and found 

 to contain mature embryos. 



SUMMARY 



1. The results of these experiments show that the intermediate 

 (cysticercoid) stage of Choanotaenia infundihuliformis occurs in the 

 common house-fly Musca domestica. The results were obtained by 

 feeding flies on eggs of the tapeworm and raising cysticercoids in 

 a fly ; also by feeding chicks on flies and raising the worms in the 

 birds. By morphological comparison of the cysticercoid and adult 

 they are shown to be identical. Results from experiments by feed- 

 ing flies on eggs from Davainea cesticillus and Davainea tetragona 

 were negative. 



2. The habits of the birds are important factors to be con- 

 sidered in experimental work for life history studies. Certain in- 

 sects are found in great numbers around chicken houses and 

 yards and are readily eaten by the birds. Flies are known to con- 

 tain the larval stage of one species of cestode, and some other 

 species of insects are to be considered as probable intermediate 

 hosts for other species of cestodes. 



3. The symptoms and effects of the infection from tapeworms 

 vary with individual birds, age of birds, and the degree of infec- 

 tion. Birds infested with worms display an emaciated, unthrifty 

 condition, an unnatural desire for food and water, and a marked 

 diarrhea with droppings of a characteristic yellowish-brown color. 



4. The control of tapeworm disease in chickens is in an unset- 

 tled condition. Little can be done until more is known concerning 

 life histories of worms. Preventive measures are urged rather 



