378 MAINE AGRICULTURAI^ EXPERIMENT STATION. I912.. 



The essential facts brought out in this study of fecundity 

 appear to me to be the following: 



1. The record of fecundity of a hen, taken by and of itself 

 alone, gives no definite, reliable indication from which the pro- 

 bable egg production of her daughters may be predicted. Fur- 

 thermore mass selection on the basis of the fecundity records of 

 females alone, even though long continued and stringent in char- 

 acter, failed completely to produce any steady change in type in 

 the direction of selection. 



2. Fectmdity must, however, be inherited since (a) there 

 are widely distinct and permanent (under ordinary breeding) 

 differences in respect of degree of fecundity between different 

 standard breeds of fowls commonly kept by poultrymen, and 

 (b) a study of pedigree records of poultry at once discovers 

 pedigree lines (in some measure inbred of course) in each of 

 which a definite, particular degree of fecundity constantly reap- 

 pears generation after generation, the 'line' thus 'breeding true' 

 in this particular. With all birds (in which such a phenomenon 

 as that noted under b occurs) kept under the same general en- 

 vironmental conditions such a result can only mean that the 

 character is in some manner inherited. 



The facts set forth in paragraphs i and 2 have been presented, 

 and, I believe, fully substantiated by clean-cut and extensive 

 evidence, in previous papers from this laboratory. In the pres- 

 ent paper it is further shown that : 



3. The basis for observed variations in fecundity is not ana- 

 tomical. The number of visible oocytes on the ovary bears no 

 definite or constant relation to the actually realized egg produc- 

 tion. 



4. This can only mean that observed differences ( variations > 

 in actual egg productions depend up on differences in the com- 

 plex physiological mechanism concerned with the maturation of 

 oocytes and ovidation. 



5. A study of winter egg production (taken for practical 

 purposes as that from the beginning of the laying year in the 

 early fall tO' March i ) proves that this is the best available meas- 

 ure of innate capacity in respect to fecundity, primarily because 

 it represents the laying cycle in which the widest difference 



