POULTRY NOTES — 1909. lOI 



is of the highest importance to have as a control a flock of birds 

 whose prodviction over a long pefiod of time and under different 

 circumstances is known. The 11 years continuous trap nest 

 records which we have here for the Barred Rock birds is a very 

 important help in work like the present. 



(5) The egg production of the winter period (November 

 I to March i ) of the laying year, furnishes practically the only 

 data of any use in discussing the problem of the inher- 

 itance of production. This period represents a natural unit in 

 the reproductive cycle in the bird's life. Practically nothing is 

 to be gained by studying the production of other periods of the 

 laying year, so far at least as problems of inheritance and breed- 

 ing of egg productivity are concerned.* The only exception to 

 this statement is with regard to the fall (September i to No- 

 vember I ) production of the pullet year. This is, in the laying 

 cycle, a kind of "pre-winter" period. Its production is an arti- 

 ficial result of breeding and domestication in the same way that 

 the winter production is. 



The raw data for the winter egg production of the different 

 hybrids and pure bred birds are given in Table lo. This table 

 shows the frequency distributions of egg production. 



*Cf. for discussion of this matter, Pearl, R., and Surface, F. M. A 

 Biometrical Study of Egg Production in the Domestic Fowl. II. The 

 Seasonal Distribution of Egg Production. U. S. Dept. Agr. Bur of 

 Anim. Indus. Bulletin no, Part II. In press. 



