inheritance; of fecundity in domestic fowe. 287 



appeared to carry a normal number of oocytes. In general it 

 was anatomically normal, but physiologically in the state of de- 

 velopment 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 fecun- 

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



Fig. 450. 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 ex- 

 planation. 



groups 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 condi- 

 tions of domestication 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 metabolic demands, which under wild condi- 



