CESTODE INFECTION IN CHICKENS 



231 



in the house until after the effects of the second dose have passed 

 off. During the time that they are confined the droppings should 

 be collected often and lots of lime used about the coop and over 

 the droppings to keep away the insects. In a flock the treatment 

 would have to be repeated from time to time whenever the birds 

 became infected again. Further experimental evidence must be ob- 

 tained before much can be said in regard to details of this method 

 of treatment, especially as to the amount of the alkali to be used. 

 A large amount would be harmful to the intestinal mucosa, while a 

 small amount would have little if any effect upon the parasites. 



Feeding Experiments for Infection. Chickens in the vicin- 

 ity of Hardy, Nebraska, were heavily infested with tapeworms, and 

 young birds were found to be more heavily infested than the adults. 

 This led to investigations concerning the reason for the difference 

 in the infestation of the adult and young birds when they were to- 

 gether in the same environment and fed on the same diet. 



The summer of 1913 was very dry in the locality which was a 

 factor in keeping the numerous varieties of insects down to a min- 

 imum, because the drought interfered with their breeding. Upon 

 observation it was found that only two kinds of insects were present 

 in any abundance about the haunts of the birds. Those were the 

 ground beetle Tenehrio and flies. The stable fly, Stomoxys calci- 

 trans, which usually breeds in wet, decaying straw, was very scarce 

 because its breeding places had dried up. The house flies were 

 very abundant everywhere. 



The reason why the adults should be only slightly infested 

 with parasites, while the young and growing birds harbored so many, 

 was then the subject for observation. The birds were watched in 

 their haunts and their habits studied. It was soon noticed that 

 the young birds, when in their resting places in the shade of a tree 

 or a building, were busy the whole time pursuing flies and very 

 often caught their prey, while the adults paid little or no attention 

 to the flies. This led to the conclusion that flies might have some- 

 thing to do with the transmission of the worms to the birds. 



With a view to testing this hypothesis, experiments were car- 

 ried on with the worms that were most common in the birds. 

 These species were Davainea cesticillus, Davainea tetragona, and 

 Choanotae7iia infundibuliformis. 



Segments of these worms were teased apart so that the eggs or 

 embryos were set free in a drop of water, and this was fed to flies 



