DISEASES OF POULTRY. 155 



lodged at this point and be held there for an indefinite 

 time. As the temperature of the bird's body is that 

 most suitable for incubation and for the development 

 of the embryo, it is plain that a fertile egg arrested in 

 the oviduct must soon undergo important changes. 

 For this reason some eggs have the odor and taste 

 that are familiar in connection with stale eggs, al- 

 though they are newly lain. In rare cases, the egg 

 may be arrested a sufiScient time to allow the embryo 

 to become more or less developed. Megnin states that 

 he removed an egg from a fowl, in making a post- 

 mortem examination, which contained an embryo upon 

 which the skin and feathers were already formed. 

 Fortunately for the reputation of the egg-producer, 

 such cases seldom occur, and it is doubtful if the hen 

 would succeed unaided in laying an egg which had 

 been retained long enough to allow the embryo to 

 develop. Some stale eggs may, however, he account- 

 ed for by prolonged retention in the oviduct. 



PARASITES IN EGGS. 



As the egg traverses the greater part of the oviduct, 

 and receives in that tube several layers of albumen be- 

 fore the shell is formed, it is not difficult to under- 

 stand how any parasites which gain entrance to the 

 oviduct may be caught in the albumen and imprisoned 

 within the shell. The lower part of the oviduct has a 

 free opening into the cloaca for the passage of the egg, 

 and it is not surprising that parasites occasionally find 

 their way along this channel. The parasite most fre- 

 quently found in the egg is the Cephalogonimus ovatus 

 (Distoma ovatum), a small fluke which has its habitat 

 in the bursa of Fabricius. More rarely, the common 

 round worm known as the Heterakis perspicillujn 

 ( Heterakis inflexa, Ascaris inflexa) is observed. 

 Thescitwo worms evidently pass into the oviduct from 



