inheritance; op fecundity in domestic eowl. 377 



genetic laws, but the point is that we do not now know scarcely 

 anything definite (i.e., scientifically exact) about the phenomena, 

 to say nothing of their underlying laws. The richness of the 

 field which still remains quite unworked on the purely physio- 

 logical side of genetics is, I think, only appreciated by the ex- 

 perienced breeder. 



Summary and Discussion of Resui^ts 



THE facts and their INTERPRETATION 



In this -paper is presented a detailed analysis and interpreta- 

 tion of a rather extensive series of data regarding the inherit- 

 ance of fecundity in the domestic fowl. The basic data are de- 

 rived from trap-nest records extending over a period of years. 

 They include records from (a) pure Barred Plymouth Rocks; 

 (b) Cornish Indian Games; (c) the P-- individuals obtained by 

 reciprocally crossing these two breeds; and (d) the P? individ- 

 uals obtained by mating the Fi's inter se and back upon the par- 

 ent forms in all possible combinations. The fully-pedigreed ma- 

 terial made use of in this present paper includes something over 

 a thousand adult females, each of which was trap-nested for at 

 least one year, and many for a longer period. This material 

 covers four generations. The birds of the fifth generation have 

 just completed their winter records at the time of writing. Be- 

 sides this fully pedigreed material, the collection and study of 

 which has occupied five years there was available as a founda- 

 tion, without which the results discussed in this page could not 

 have been reached, nine years of continuous trap-nest records 

 for Barred Plymouth Rocks, involving thousands of birds, which 

 had been subjected during this long period to mass selection for 

 increased egg production. 



Altogether it may, fairly be said that the material on which 

 this paper is based is (a) large in amount, (b) extensive in 

 character, and (r ) in quality as accurate as it is humanly possi- 

 ble to get records of the egg production of fowls (Pearl 31). 

 On these accounts the facts presented are worthy of careful con- 

 sideration, and have a permanent value quite apart from any 

 interpretation which ma}' be put upon them. 



