No. 552] INHERITANCE OF FECUNDITY 699 



can only mean that the character is in some manner in- 

 herited. 



The facts set forth in paragraphs 1 and 2 have been 

 presented, and, I believe, fully substantiated by exten- 

 sive evidence, in previous papers from this laboratory. 

 It is now further shown that : 



3. The basis for observed variations in fecundity is 

 not anatomical. The number of visible oocytes on the 

 ovary bears no definite or constant relation to the actu- 

 ally realized egg production. This is shown by the fig- 

 ures presented in Table I. These give the counts of the 

 number of oocytes on the ovary visible to the unaided eye 

 in the case of a number of individuals. It will be under- 

 stood that it is not contended that such counts give an 

 accurate measure of the total oocyte content of the 

 ovary. The figures, however, are so greatly in excess of 

 what a hen actually ever lays that it may be quite safely 

 concluded that in normal cases (where no accident or 

 operation has induced regenerative processes in the 

 ovary) all the eggs which will ever be laid (and usually 

 more) are included among those visible to the eye, on an 

 adult fowl's ovary. 



From this table it is evident that when one bird has a 

 winter record of twice what another bird has it is not 

 because the first has twice as many oocytes in the ovary. 

 On the contrary it appears that all birds have an ana- 

 tomical endowment entirely sufficient for a very high de- 

 gree of fecundity, and in point of fact quite equal to that 

 possessed by birds which actually accomplish a high 

 record of fecundity. Whether or not such high fecund- 

 ity is actually realized evidently depends then upon the 

 influence of additional factors beyond the anatomical 

 basis. 



4. This can only mean that observed differences (vari- 

 ations) in actual egg productions depend upon differ- 

 ences in the complex physiological mechanism concerned 

 with the maturation of oocytes and ovulation. 



