MAINE AGRiCULTURAL EXPERIMENT STATION. 1/ 



pie egg production or feather marking, that unless special at- 

 tention is paid to tliis point there will tend to be a progressive 

 deterioration in the average size of the birds. This is particu- 

 larly liable to happen when one is breeding for egg production. 

 To counteract this tendency special attention must be paid to 

 the size of the breeding stock, making it a rule never to use as 

 a breeder any bird, whatever the other excellencies may be, 

 which does not attain a certain weight standard set by the 

 breeder. 



What has been sai 1 regarding size is only a special case of 

 the general rule of breeding that always the effort in selecting 

 breeders should be towards all-round excellence. vSelection for 

 any one character alone — as for example egg production — 

 with an entire disregard of all other characters of the birds 

 will, in comparatively few generations, defeat its own end. Tt 

 will be found that the stock has deteriorated quite as much in 

 regard to some important qualities as it may have gained in 

 respect to the character for which selection was made. 



While it is not possible here to enter upon an exhaustive dis- 

 cussion of the subject of breeding for egg production a word 

 may. be said regarding the results of the Maine Agricultural 

 Experiment Station along this line. From long continued 

 experiments it appears to be conclusively demonstrated that 

 the male bird has a hitherto unsuspected importance in the 

 transmission of high-laying qualities to the progeny. Egg pro- 

 duction, in the Ijarred Plymouth Rock fowl at least, appears 

 to depend upon two separately inherited physiological factors. 

 Either of these factors when present alone in a bird makes it 

 a poor or mediocre layer. If both factors are present together 

 the bird is a high producer. The novel feature of the case lies 

 in the point that the factor upon which high production depends 

 (i. e., which must be present if the bird is to be a high pro- 

 ducer) is never transmitte:l in inheritance from a mother to 

 her daughters, but only to her sons. Tt behaves, in other words 

 as a sex-linked character. The male bird which possesses this 

 hereditary factor for high production may however transmit 

 it both to his sons and his daughters. It thus appears that the 

 high egg productiveness exhibited by some pullets or hens is 

 always directly inherited from tlie sire, and not at all directly 

 from the dam, though the sire himself may very likely have 

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