THE 



AMERICAN NATURALIST 



Vol. LII. February-March, 1918 No. 614 



INTERNAL FACTORS INFLUENCING EGG PRO- 

 DUCTION IN THE RHODE ISLAND RED 

 BREED OF DOMESTIC FOWL 



A Survey of the Problem of Egg Production and a 

 Preliminary Analysis of an Egg Record into its 



DR. H. D. GOODALE 

 Introduction 



A survey of the problem of egg production, such as is 

 made in the present paper, seems desirable at the present 

 time because of the great interest taken in breeding for 

 increased egg production. While the various factors dis- 

 cussed are familiar, to a degree at least, to most poultry 

 keepers, nevertheless they are ignored in breeding prac- 

 tise and reliance placed upon the numerical record alone 

 as a sufficiently detailed and accurate description of a 

 hen's performance, although, as will be pointed out in a 

 later section, identical numerical records result from 

 quite diverse combinations of factors. 



The point of view which we have been led to adopt may 

 be stated in one form as follows: The egg record of a hen, 

 expressed as a given number of eggs per unit of time and 

 taken by itself, is not a sufficient measure or description 

 of egg production, even under a favorable environment, 

 for the record is the result of the interaction of a number 

 of innate factors. Some of these factors, such as rate of 

 growth, are quite distinct from egg production, while 

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