STUDIES ON THE PHYSIOLOGY OF REPRODUCTION 

 IN THE DOMESTIC FOWL 



X. FUKTHER DATA ON SOMATIC AND GENETIC STERILITY^ 

 MAYNIE R. CURTIS AND RAYMOND PEARL 



Some time ago one of the authors (Pearl '12) called attention 

 to the fact that any single record of non-production or low 

 production could not be accepted as evidence for the absence 

 of the genetic factor for high production, since the failure of a 

 bird to lay might be due entirely to somatic (physiological) 

 causes. Later a detailed description of two such cases was 

 published (Pearl and Curtis '14). In both of these instances 

 the ovarian eggs were formed, but did not enter the oviduct. 

 In one case the funnel mouth was too small to admit a full-sized 

 mature yolk, and in the other there was an apparent lack of 

 tone in the muscles of the oviduct and its ligaments. In both 

 cases the yolks were ovulated into the body cavity and resorbed 

 without causing any apparent disturbance in metabolism. 



The purpose of the present paper is to record some recent 

 observations on other cases of the same general nature. 



MATERIAL 



On September 1, 1914, there were in the Maine Station's 

 flock of first-year birds, eight apparently healthy birds which 

 had laid few or no eggs, and one which had laid well up to the 

 beginning of the breeding season and then stopped laying. All 

 of these birds were hatched between April 7 and May 21, 1913. 

 Several were from high laying strains. In order to determine 

 if possible the cause of the partial or complete sterility, these 

 nine birds were killed and carefully examined. The observations 



^ Papers from the Biological Laboratory of the Maine Agricultural Experi- 

 ment Station, No. 73. 



45 



