REPRODUCTION IN THE DOMESTIC FOWL. 



187 



the middle was a string of coagulation fibers like untwisted 

 chalazal threads. Mixed with these at certain points were small 

 droplets of yolk. The membrane covering the dwarf egg was 

 complete at one end and open at the other. The albumen 

 surrounding the chalazal-like core was thick. The chalazal 

 core surrounded by thick albumen continued beyond the mem- 

 brane at the open end. This naked portion separated definitely 

 from the surrounding albumen when the dwarf egg was taken 

 from the albumen. Evidently this cylindrical dwarf egg had 

 passed partly into the isthmus and had then been returned 

 into the albumen region where it became enclosed in the suc- 

 ceeding egg. 



II. DOUBLE EGGS IN WHICH THE ENCLOSING EGG is A SET OF 



EGG ENVELOPES WITH NO APPARENT NUCLEUS 



EXCEPT THE ENCLOSED EGG. 



(a) The Enclosed Egg was a Normal Egg or at Least Had a Normal 

 Yolk in Specimens 6, 7, 8, Q and 10. 



Specimen 6 was laid by a normal bird belonging to the Maine 

 Station flock. In external appearance it resembled a large hard- 



FlG. 3. Diagram showing the structure of double egg No. 6. a = albumen; 

 m = membrane; 5 = shell, y = normal yolk. 



shelled double-yolked egg. A diagram showing the structure 

 of this egg is shown in Fig. 3. The entire egg weighed 94.74 gm. 

 When the egg was opened it was found to contain a membrane- 

 covered egg surrounded by a layer of thick and a layer of thin 

 albumen. This albumen weighed 57.39 gm. The weight of 



