THE GAPE-WORM. 81 



during development. On the earthworm being 

 eaten by the fowl, the embryonic Gape-worms are 

 released in the digestive organs, and then find their 

 way back to the air-passages, take up their per- 

 manent abode there, and reach maturity. 



Unfortunately for this theory, we find that Gapes 

 appears in young chicks long before they could have 

 eaten earthworms. Again, Gapes appears in fowls 

 on land where earthworms do not exist. The Green 

 Woodpecker, the Martin, and Swift suffer from this 

 parasitic disease, yet they do not eat earthworms. 



It is quite possible, nevertheless, that fowls may 

 take in embryos from eating, as they ravenously do, 

 the earthworms. These useful annelids would doubt- 

 less take in the ova in the soil that passes in such 

 quantities through their bodies. This is quite dif- 

 ferent to assuming that the earthworm is an inter- 

 mediate host : it is simply a chance occurrence. 



There is very little doubt but that Gapes is spread 

 by direct infection derived from the ova and embryos 

 brought up in the expectorations of the fowls. 

 These are taken from the soil and from polluted 

 drinking-water — wild birds playing an important 

 part in the distribution of this pest. I have trans- 

 mitted this disease direct from one bird to another 

 with ease ; whilst water polluted with the ova taken 

 from mature worms gave the complaint to seven 

 out of nine fowls drinking it. 



G 



