INHERITANCE OF FECUNDITY 157 



but pbysiologicall}^ in the state of development appropriate to a 

 five or six months old pullet just about to lay. The same was true 

 of the oviduct. In this case the physiological factor or factors 

 necessary to the bringing about of ovulation were simply totally 

 lacking, in an otherwise perfectly normal bird. 



Some other cases demonstrating the same thing might be cited 

 from our records, but this will suffice for present purposes. 



Turning now to the physiological factors involved in fecundity 

 it would appear that there are at least two such factors or groups 



Fig. 1 Photograph (about twice natural size) of ovary of hen no. 8051. Note 

 the presence of a large number of oocytes; none of which is enlarging in preparation 

 for laying. See text for further explanation. 



of factors. The first of these may be designated as the 'normal 

 ovulation' factor. By this is meant the complex of physiological 

 conditions which taken together determine the laying of about 

 such a number of eggs as represents the normal reproductive 

 activity of the wild Gallus bankiva. Under conditions of domes- 

 tication the activity of this normal ovulation factor will mean the 

 production of more eggs than under wild conditions. Continued 

 egg production involves certain definite and rather severe meta- 

 bolic demands, which under wild conditions will not always, or 



