'/-" 



l'(t^l.■|■u^■ Disi'ASKS ami tiikik inkat.mi'.nt, 



material is far less common than it used to be; over-feeding or 

 over-stimulation prol)al)ly more so." 



Small. Vollclcss Eggs. These little ei,^gs, variously called 

 '•wind-eggs." "cock eggs," "witch eggs," "luck eggs," etc., are 

 familiar to every poultry keeper. They contain no definitely 

 formed yolk, and to the casual observer seem to consist of 

 nothing but a small shell filled with white. The laying of one 

 of these eggs is popularly supposed to mark the end of a laying 

 period. This belief is without foundation in fact. They may 

 be produced at any time. Unpublished data collected over a 

 period of years at this Station in regard to such eggs indicate 

 that three factors are fundamentally concerned in their pro- 

 duction. The^^e arc: — 



1 . The bird must l)e in an active laying condition ; the more 

 pronounced the degree of physiological activity of the oviduct 

 the more likel\- arc these eggs to be produced. 



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

 serve as the stimulus wdiich shall start the albumen glands se- 

 creting. 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 fi. e.. the separation of a yolk from the 

 ovary) must precede the secretion of albumen around the for- 

 eign body to form one of these eggs. 



Double and Triple Yolked Eggs. Eggs wdth two yolks are. 

 of course, quite common. They result from a disturbance of 

 the time relations of ovulation, of such nature that two volks 



Fig. 42. Triple yullvca egg. (Uriginal). 



