REPRODUCTION IN THE DOMESTIC FOWL. 2O5 



will be a normal egg with a large percentage of albumen or in 

 case the returned egg meets its successor, a double-yolked egg. 



15. If the backward movement of an egg in any stage does not 

 stop too soon, the partly or fully formed egg will be expelled 

 from the funnel mouth into the body cavity. 



16. In case the oviduct is naturally or artificially closed the 

 eggs are regularly expelled by forcing them out the funnel 

 mouth. 



17. A double egg then is the result of a combination of normal 

 and abnormal processes which when combined in other pro- 

 portions result in other abnormal phenomena of egg production. 



1 8. An egg may move backward and forward several times 

 in the duct as is shown by the production of an egg enclosed 

 within a series of concentric egg membranes separated by thick 

 albumen. 



LITERATURE CITED. 



1. Bonnet. 



'83 Das Vogelei. Deutsche Zeitschrift fur Thiermedicin, Vol. IX., pp. 

 239-252. 



2. Curtis, M. R. 



'14 Studies on the Physiology of Reproduction in the Domestic Fowl. VI. 

 Double and Triple Yolked Eggs. BIOL. BUL., Vol. XXVI., pp. 55-83. 



3. Curtis, M. R. 



'15 Studies on the Physiology of Reproduction in the Domestic Fowl. XI. 

 The Relation of Simultaneous Ovulation to the Production of Double- 

 yolked Eggs. Jour. Agr. Research, Vol. III., pp. 375~386. 



4. Curtis, M. R. 



'15 Studies on the Physiology of Reproduction in the Domestic Fowl. 

 XII. On an Abnormality of the Oviduct and Its Effect upon Repro- 

 duction. BIOL. BUL., Vol. XXVIII., pp. 154-162. 



5. Devaine, C. 



'61 Memoire sur les anomalies de 1'oeuf. Compt. Rend, et Mem. Soc. 

 Biol., Paris, Ser. 3, T. 2, pp. 183-266. 



6. von Durski, S. P. 



'07 Die pathologischen Veranderungen des Eies und Eileiters bei den 

 Vogeln. Inaugural-Dissertation. Berlin. 



7. Gruvel, A. 



'02 Sur un cas special d'oeuf teratologique. Proc. Verb. Soc. Sci. Phys. 

 Nat. Bordeaux Ann., 1901-1902, pp. 72-76. 



8. Hargitt, C. W. 



'12 Double Eggs. American Naturalist, Vol. XLVI., pp. 556-560. 



9. Hicks, C. J. and Visher, J. W. 



'15 Contributions to the Physiology of the Stomach. XXVII. The 

 Mechanism of Regurgitation of Duodenal Contents into the Stomach. 

 Amer. Jour, of Physiol., Vol. XXXIX., pp. 1-8. 



