1030 Journal of Agricultural Research vol. vi.no. 25 



nucleus in each of the other cases was hardened secretion. The inclosed 

 egg was a very small-stalked dwarf egg with a hard shell. There was no 

 yolk in either the inner or outer egg. 



An egg similar to the one just described but much larger (weight, 

 32 gm.) was produced by a 2^-year-old bird which had laid normally 

 until the end of her second breeding season. She stopped laying about 

 the middle of June and showed no evidence of reproductive activity 

 until the middle of August. She then began making nesting records. 

 On the 25th she produced the double dwarf egg. A week later she 

 was sold. The inclosed egg was a hard-shelled, stalked, dwarf egg 

 which weighed 7 gm. The end of the stalk was open. This egg con- 

 tained a mass of chalazal fibers and thin albumen. The long axis of the 

 inclosed egg lay in the long axis of the inclosing egg. Coagulated albu- 

 men fibers like untwisted chalazae were attached to both ends of the egg. 

 The mass at the closed end of the inner egg contained a small cluster of 

 yolk granules and a small lump of hardened secretion. The outer 

 egg had both thick and thin albumen, normal egg membrane, and hard 

 shell. 



Four other cases have occurred at the Station plant where a very small 

 dwarf egg has been the nucleus for a larger dwarf egg. In none of these 

 cases was there any yolk in the outer egg, although in two of them 

 there was a small amount of yolk in the inner egg. In each case the 

 dwarf egg was covered by an egg membrane without shell. Each of the 

 outer eggs had normal egg membranes and shell. In three cases there 

 were bunches of coagulated albumen fibers resembling chalazae attached 

 to the poles of the inclosed dwarf egg. In each case the bird producing 

 the egg was a normal heavy-laying bird and the egg occurred in a normal 

 clutch of from two to five eggs. In each case the double egg was the 

 only abnormal egg ever produced by the bird. 



It thus seems that in normal birds in active laying condition a dwarf 

 egg may be forced up the duct and may furnish the stimulus for the 

 formation of a set of egg envelopes in which it becomes inclosed. 



D. — EVIDENCE FROM EGG RECORDS AND EGG CONTENTS 



It has been shown above that in cases of dwarf -egg producers on which 

 autopsies were made, both normal and abnormal birds produced dwarf 

 eggs only when the ovary was in active condition. All cases on which 

 autopsies have been made with a dwarf egg in the oviduct, or within 

 a few hours after a dwarf egg was laid, showed large empty follicles. 

 Every case but one showed also that a yolk had been ovulated at almost 

 precisely the time the secretion of the egg envelopes of the dwarf egg 

 began. In the other case the ovary contained a series of absorbing 

 follicles, two of which were very large, indicating that both had been 

 discharged within two or three days at most. One of these had furnished 



