REPRODUCTION IN THE DOMESTIC FOWL. 2O3 



usually absorbed without difficulty. When the reversal of direc- 

 tion is of less extent the result may be a normal egg with a large 

 percentage of albumen or rarely it may be a double-yolked egg. 



SUMMARY. 



1. A membrane-covered or hard-shelled normal or dwarf 

 egg may be returned up the duct and may either meet its successor 

 and return with it, becoming enclosed in a common set of egg 

 envelopes, or not meeting its successor it may again be forced 

 through the duct stimulating the secretion of a set of egg en- 

 velopes around itself. 



2. The number of egg envelopes common to the enclosed egg 

 and the yolk of the enclosing egg or the number of egg envelopes 

 which surround the enclosed egg when the enclosing egg has no 

 yolk depends apparently on the level of the duct at which the 

 enclosed egg resumes its normal direction toward the cloaca. 



3. The enclosed egg is usually forced up the duct without 

 turning on its axis but occasionally the poles are reversed. 



4. A similar reversal of poles sometimes occurs in normal 

 laying and it seems probable that in both cases this turning takes 

 place in the uterus when the first powerful contractions of the 

 uterus brings the outwardly directed end of the egg slightly above 

 the opening from the shell gland into the vagina and tangentially 

 against the curved caudo-dorsal angle of the uterus. 



5. The enclosed egg usually precedes its successor through 

 the duct and, therefore, usually lies in the pointed or anterior 

 end of the enclosing egg, while the yolk of the enclosing egg lies 

 in the blunt or posterior end. 



6. However, in two known cases where the enclosed egg united 

 with its successor after the latter had received practically all its 

 thick albumen there is evidence that the two eggs came side by 

 side in the duct with their long axis parallel and in one case they 

 certainly passed through the duct side by side with their long 

 axes parallel to each other and also parallel to the long axis of 

 the duct. 



7. There has been one case described with the yolk in the 

 pointed and the enclosed egg in the blunt end of the enclosing 

 egg. There is some doubt about the accuracy of this observation 

 but it is possible that two eggs can pass in the duct. 



