DISEASES OF POULTRY. 



47 



Fig'- 8.— Chicken affected with crapes. 



the eggs and emV)ryos are set free by the disintegra- 

 tion of the worm. The eggs require warmth and 

 moisture to hatch, and similar conditions are needed 

 for the life of the embryos. These newly -hatched em- 

 bryos may be at once taken up l)y birds, with contami- 

 nated food or drink, and thus cause infection; or they 

 may be taken into the digestive canal of earth worms, 

 as has been shown l)y Walker, and be carried for some 

 time by such earth worms. It has been shown conclu- 

 sively that earth worms from infected poultry runs will 

 cause gapes if fed to chickens. Whether or not the 

 earth worm plays an important part in sheltering and 

 protecting the embryos of the syngamus and in thus 

 maintaining the infection upon certain premises is not 

 definitely known. 



Walker considers the earth worm a very important 



