296 MAINE AGRICULTURAL EXPERIMENT STATION. I915. 



2. This difterence is in the direction of a substantially higher 

 mean production at the present time, when tested on flocks of 

 large size. 



3. The increase in flock average productivity is most pro- 

 nounced in respect to winter production, which is the laying 

 cycle to which especial attention has been given in the breeding. 



4. The cause of this increase in flock productivity appears, 

 with a degree of probability which is very high and amounts 

 nearly to certainty, to be that the method of breeding the stock 

 now followed is more closely in accord with the mode of inherit- 

 ance of fecundity than was the simple m.ass-selection practised 

 in the earlier period. 



5. The result announced in earlier papers that high fecun- 

 dity is a sex-linked character, for which the female is heterozy- 

 gous, has been confirmed by practical poultrymen in their 

 breeding operations. 



STUDIES OX THE PHYSIOLOGY OF REPRODUCTION 

 IN THE DO^IESTIC FOWL. 



XIII. On the Failure of Extract of Pituitary Body 

 (Anterior Lobe) to Activate the Resting Ovary. 



From the evidence presented in this paper it appears to be 

 clearly established that the substance of the anterior lobe of the 

 pituitary body of the cow, when injected into the abdominal 

 cavity of hens in which the ovary is in a completely resting 

 condition, does not cause an activation of the ovary, in the sense 

 of inducing ovulation at an earlier date than that at which it 

 would normally occur. 



*This is an abstract of a paper by Raymond Pearl and Frank M. 

 Surface, having the same title and published in Jourrial of Biological 

 Chemistry, Vol. XXI, pp. 95-101. 1915. 



