abstracts. 28/ 



Studies on the Physioeogy of Reproduction in the Domes- 

 tic Fowl. x. Further Data on Somatic 

 AND Genetic Sterility.* 



This is a study of certain cases of partial or complete steril- 

 ity in the fowl, having for its object to get further light on 

 the cause of such sterility. 



The chief results may be summarized as follows: 



1. Birds which are hereditarily high layers may fail to 

 make good performance records because for some anatomical 

 reason it is impossible for yolks to enter the oviduct. 



2. Birds which ovulate, or return partly formed eggs, into 

 the body cavity usually show the nesting instinct. 



•3. The nesting records show a rhythm similar to egg records 

 of normal 'birds and it seems probable that they are the normal 

 resultant of the ovulation. 



4. Data given in this paper justify the following statements. 



A. In case of stoppage of the duct at any level the duct 

 on both sides of the point of stoppage passes through the 

 same cyclic changes coordinated with the cyclic changes m 

 the ovary as a normal unobstructed duct. The duct functions 

 only as far as it receives the stimulus of the advancing egg. 



B. Absence of pressure from the funnel does not prevent 

 or apparently greatly retard ovulation. Increased internal pres- 

 sure may therefore be the most important factor in normal 

 ovulation. 



C. Yolks of partly or fully formed eggs may be absorbed 

 rapidly and in large numbers from the peritoneal surface with- 

 out causing any serious derangement of normal metabolic pro- 

 cesses. 



*This is an abstract of a paper bearing the same title by Maynie R. 

 Curtis and Raymond Pearl, now in press in the Journal of Experimental 

 Zoology. 



