274 Dl^-e.s- of Poult nj 



published data collected over a i)eriod of years at this Station 

 in regard to such eggs indicate that three factors are funda- 

 mentally concerned in their production. These are : 



1. The bird must be in an active laying condition; the 

 more pronounced the degree of physiological activity of 

 the oviduct, the more likely are these eggs to be produced. 



2. There must be some foreign body, however minute, to 

 serve as the stimulus which shall start the albumen glands 

 secreting. This foreign body may be either a minute piece 

 of hardened albumen, a bit of coagulated blood, a small 

 piece of yolk which has escaped from a ruptured yolk, etc. 



3. It seems likely, though this is a point not yet definitely 

 settled, that ovulation (i.e., the separation of a yolk from 

 the ovary) must precede the secretion of albumen around 

 the foreign body to form one of these eggs. 



Double and Triple Yolked Eggs. — Eggs with two yolks 

 are, of course, quite common. They result from a disturb- 

 ance of the time relations of ovulation, of such nature that 

 two yolks get into the oviduct at nearly the same time and 

 become surrounded by common layers of albumen. 



Eggs with three yolks are very rare. An egg of this kind 

 laid by a pullet at this Station is shown in Fig. 58. 



Studies made by one of the authors ^ have thrown consider- 

 able light on the general problem of the cause and nature of 

 multiple-yolked eggs. Summarized some of the chief re- 

 sults were as follows : As to frequency it appears that the 

 Maine Station flock, over a long period of time, produces 

 531 single-yolked eggs to every double-yolked egg. That is, 



1 Curtis, M. R., "Studies on the Physiology of Reproduction in 

 the Domestic Fowl." VI. Double- and Triple-Yolked Eggs. Biol. 

 Bui., Vol. XXVI, pp. 55-83, 1914. 



"Studies on the Physiology of Reproduction in the Domes- 

 tic Fowl." XI. Relation of Simultaneous Ovulation to the 

 Production of Double- Yolked Eggs. Jour. Agr. Research, Vol. Ill, 

 pp. 375-385, 1915. 



