232 JOHN E. GUTBERLET 



of the species: Musca domestica, Stomoxys calcitrans, and Calli- 

 phora vomitaria. 



Only a few Calliphora could be obtained and these did not 

 live long under experimental conditions. This species of fly does 

 not frequent places where it would be likely to become the inter- 

 mediate host of any of the chicken cestodes, as it always remains in 

 cool, damp, and usually dark places, unless it can find carrion. 

 However, on cool, dark, damp days it does appear in chicken yards, 

 but its occurrence there is not frequent. Some Stomoxys were used, 

 but in no case did they live long in captivity. -* 



Musca domestica lived much longer than either of the others, 

 even though it was difficult to keep them alive for a long period. 

 After a great deal of experimentation it was found that they could 

 be kept alive in a cage for twelve or thirteen days, and in one ex- 

 treme case some were kept alive for twenty-one days. The flies in 

 captivity were fed on blood, liver and spleen. These were found to 

 be the best foods. 



The oldest proglottids on the worm were usually taken for 

 feeding to flies, and also some of the free segments in the intestine 

 were used. The use of the oldest proglottids proved to be an error 

 in the case of Choanotaenia infundibtdiformis, because it was found 

 later that in this species the oldest segments separate from the 

 worm before they are entirely mature, but proglottids that have been 

 free in the intestine for some time may be mature. The use of 

 proglottids that were not entirely mature for feeding flies was an 

 error in my experiments which may account for so few infections. 



Davainea cesticillus. In a series of experiments 107 flies of 

 the species Musca domestica were fed on the eggs from proglottids 

 of Davainea cesticillus. Some were killed and preserved each day 

 from the beginning of the experiment until the tenth day, when the 

 remaining flies died, except in one case four were kept alive for 

 twenty-one days. These were all sectioned with the exception of 

 five, which were dissected. No stages of the cestodes were found in 

 any of the flies when examined. 



During the experiment microscopic examinations were made of 

 a great number of the droppings of the flies and no eggs or embryos 

 of the worms could be found in any case. It is certain that the 

 flies got some of the eggs because they were numerous in the mater- 

 ial that was fed to them. The flies would lap up all the water in 

 which the eggs floated and would then suck on the fragments of 



