THE TURKEY IMPORTANT IN THE SPREAD OF GAPEWORMS. 3 



a year old. That turkeys above 3 years of age may harbor gape- 

 worms is established by the fact that a turkey which was kept at the 

 Bureau of Animal Industry Experiment Station, Bethesda, Md., for 

 three years after it was brought there was found after its death to 

 be infested with a pair of gapeworms. 



EXPERIMENTAL WORK. 



Experiments in artificially infecting chickens of various ages with 

 gapeworms were carried out as follows : To provide material for 

 infecting the chickens, cultures were made at first from gapeworms 

 collected from the tracheas of turkeys. Later many of the worms 

 collected from the artificially infected chickens were also used in mak- 

 ing cultures. The worms were chopped into small pieces and the 

 eggs released by tearing apart the fragments of the uteri in a small 

 quantity of water. The water containing particles of worms and the 

 eggs was spread on the surface of a sterilized medium culture made 

 from chicken feces mixed with powdered animal charcoal. This was 

 kept moist in a petri dish and allowed to incubate at room tempera- 

 ture. After about two weeks' incubation a large proportion of the 

 eggs contained fully developed larvae, many of which commonly 

 hatched and continued active for long periods after hatching. The 

 cultures were then ready for use and were fed to the chickens by plac- 

 ing small portions scraped from the surface of the culture medium 

 directly into the mouth and making sure that the birds swallowed the 

 material. The chickens used in the experiments, except the adults, 

 were hatched in incubators and kept from exposure to gapeworm 

 infection until used. Usually only one feeding was given, and in 

 most cases the chicken, if it did not die earlier, was killed two weeks 

 after feeding the infectious material. Occasionally chickens were 

 killed for examination in less than two weeks after infection. The 

 tracheas and lungs were examined for gapeworms, the latter by dis- 

 section in physiological salt solution, a lens being used for the dis- 

 covery of small, incompletely developed worms; Altogether 139 

 chickens of different ages were thus fed infectious gapeworm 

 material. The results are shown below. 



Results of artificially infecting chickens with gapeworm material. 



Age of chickens when fed. 



Number 



Number 



fed. 



infected. 



47 



41 



32 



27 



32 



21 



28 



8 



Per cent 

 infected. 



1 to 4 weeks 



5 to 8 weeks 



9 to 20 weeks 



21 weeks to adult 



