1040 Journal of Agricultural Research vol. v1.N0.s5 



(26) The popular notion that a dwarf egg marks the end of a period 

 of production is without foundation. A dwarf egg is equally likely to 

 occur at any time during a clutch or litter. 



(27) A dwarf egg may be overtaken by a normal egg and form one of 

 the components of a compound egg similar to a double-yolked egg except 

 that one part is a dwarf egg. 



(28) A dwarf egg after it has received its membrane or its membrane 

 and shell may be returned up the duct and be included in the succeeding 

 normal egg, or it may act as the stimulus for the formation of a larger 

 inclosing dwarf egg. 



(29) Dwarf eggs are produced only when the ovary is in the ab- 

 solutely active condition associated with the maturing of yolks. This is 

 true whether the bird has a normal or pathological oviduct. 



(30) When the sex organs are in this condition, a mechanical stimula- 

 tion of the oviduct by an artificial yolk may result in the formation of a 

 complete set of egg envelopes. 



' (31) The mechanical stimulation need not begin at the funnel in order- 

 to be effective to the parts lower down. 



(32) The mechanical stimulation is local in its effect — that is, it is not 

 transmitted down the duct any distance below the point to which it is 

 applied. 



(33) Dwarf eggs may be and probably often are produced by the 

 stimulation of an active duct by some material particle which is not yolk. 



(34) At least 65 per cent of the dwarf eggs studied, however, were 

 initiated by an abnormal small yolk or by a part of a normal yolk. Cer- 

 tainly in some and probably in all the latter cases the rest of the yolk was 

 absorbed by the visceral peritoneum. 



(35) Neither the absolute time relation between ovulation and the 

 ability of the duct to respond to mechanical stimulation nor the nature of 

 the connection between the state of the ovary and the duct is certainly 

 known. 



(36) It is suggested that the oviduct may be sensitized by some change 

 in the internal secretion of the ovary associated with the maturation of 

 yolks. 



(37) It is also pointed out that if this is the case the change in the 

 secretion probably precedes ovulation. 



LITERATURE CITED 



(1) Bartelmez, G. W. 



1912. The bilaterality of the pigeon's egg. Pt. 1. In Jour. Morph., v. 23, no. 

 2, p. 269-328, 4 fig., 8 pi. Bibliography, p. 310-313. 



(2) Bonnet. 



1883. Das Vogelei. In Deut. Ztschr. Thiermed., Bd. 9, p. 239-252. 



(3) Curtis, Maynie R. 



191 1. An accurate method for determining the weight of the parts of the eggs 

 of birds. Maine Agr. Exp. Sta. Bui. 191, p. 93-112, fig. 73-75. 



