REPRODUCTION IN THE DOMESTIC FOWL. 185 



blunt end of the enclosing egg. The fact that the dwarf egg is 

 enclosed in only the outer thick albumen layers may readily be 

 seen from the photograph. No chalazse were visible in the 

 enclosing egg. The structure of the dwarf egg was quite com- 

 plex. It consisted of a series of four concentric egg membranes 

 separated from each other by layers of clear thick albumen. 

 Within the inner membrane was a mass of chalazal-like coagula- 

 tion fibers surrounded by thick albumen. Attached to one end 

 of the innermost egg was a mass of coagulation fibers. There 

 was no shell on any of the egg membranes except the outer one. 

 The structure of this egg indicates that a very small dwarf egg 

 passed back from the isthmus to the albumen-secreting region, 

 acquiring some chalazal fibers and a small amount of albumen. 

 It then passed into the isthmus, received another membrane, and 

 was then returned to the albumen-secreting region, where it 

 received another albumen layer. Passing again to the isthmus 

 it received its third membrane. It was again returned to the 

 albumen region where it received another layer of albumen. It 

 then passed through the isthmus into the shell gland receiving 

 an egg membrane and a thin layer of shell. It was then returned 

 again to the lower portion of the albumen-secreting region where 

 it met a normal yolk surrounded by several layers of albumen 

 and became enclosed with this in a few layers of albumen and 

 egg membrane and shell. The fact that the albumen separating 

 the concentric egg membranes of the enclosed dwarf egg was in 

 each case the clear thick albumen, secreted so far as is known 

 only in the albumen secreting region, compels the conclusion 

 that the egg passed from isthmus to albumen-secreting region 

 several times. This indicates a considerable disturbance of the 

 normal movements. Whatever the nature of this disturbance 

 the egg record of the bird shows that it was of temporary char- 

 acter, since the bird had been producing and continued to pro- 

 duce normal eggs in regular series. The double egg was the 

 first egg of a two egg clutch. It followed a four-day non-pro- 

 duction period, on the last day of which the bird nested but did 

 not lay. 



Specimen 4 was brought to the Maine Station biological 

 laboratory by Dr. O. A. Johannsen. The egg had been broken 



