INHERITANCE OF FECUNDITY 



241 



TABLE 30 

 Showing the results of mating Class 2 B.P.R. d^cf witJi high laying Barred Fi9 9 



they lacked it. The third zero bird (no. 558) was an extremely 

 interesting case. Something was at fault physiologically with her 

 reproductive organs, as a result of which she never laid an egg. 

 However, she gave clear evidence that she bore the factor Li 

 (or Lo — not both) gametically. This she did through her nesting 

 records. For some years past records have been kept in this 

 work not only of when a hen visited a nest and laid, but also when 

 she visited a nest and did not lay. A large number of records 

 have been accumulated of birds which go through the whole 

 process of nesting and laying except that they do not discharge 

 any eggs from the body. It was hoped to publish a paper on this 

 subject, which throws light on the problem of the physiology of 

 egg production, before the present paper appeared. This has 

 not been possible owing to pressure of other work, so it will be 

 necessary to take a little space here to discuss certain phases of 

 this subject. It has been shown experimentally in the laboratory 

 that if the oviduct of a normal healthy hen, with a normal ovary, 

 is ligated, transected or removed entirely, without injury to the 

 ovary, such a bird goes regularly through the entire process of 

 laying, save for the extrusion of an egg, which is physically impos- 

 sible. The 'n' (nesting) record of such a bird is precisely like a 

 normal egg record, showing the same phenomena of rhythm and 



