191 1.] Selection of Fowls for Egg Production. 659 



Comparatively little is at present known with regard to 

 the biological factors which cause improved egg production, 



or as to the laws according to which 

 Selection of Fowls these factors operate. Empirical 

 for Egg Production, methods have led to a knowledge of 



how to feed, care for, and, to some 

 extent, breed fowls with a view to a high egg production ; but 

 the biological laws underlying the process of egg production 

 are still but little understood. A valuable contribution* to 

 the subject has recently been made by Dr. Raymond Pearl 

 and Dr. F. M. Surface, based on an analysis of certain com- 

 prehensive statistics relating to egg production in certain 

 breeds of the domestic fowl which are available as the result 

 of many years' work at the Maine Agricultural Experiment 

 Station. Exact records of production have been kept at this 

 station since 1898 by the use of the trap nest, and from 1905 

 onwards the work has been conducted with the co-operation 

 of the Bureau of Animal Industry of the United States 

 Department of Agriculture. 



Material and Methods of Investigation. — The statistical 

 material dealt with in the investigation is furnished by the 

 egg records of two breeds of hens — Barred Plymouth Rocks 

 and White Wyandottes. All the birds used at the beginning 

 of the breeding experiment in 1898 were pure-bred, and had 

 for some years been bred under the direction of the late 

 Prof. G. M. Gowell. The hens used for breeding from 1898 

 onwards have been only those birds which have, between 

 November 1st of the year in which they were hatched and 

 November 1st of the following year, laid 160 or more eggs; 

 and the male birds used since 1900 have been only those from 

 hens which have laid 200 or more eggs in such a year. With 

 the exception of the first years there has been no close in- 

 breeding; no birds as closely related as first cousins are said 

 to have been bred together since the first year of the breeding 

 experiments. 



Throughout the inquiry the "first year's egg production" 

 of a hen has been taken as consisting of the trap-nest record 

 of the total number of eggs produced by that hen from 



* U.S. Dept. of Agriculture, Bureau of Animal Industry, Bulletin no, 

 Parts I. and II. 



