142 POULTRY PRODUCTION 



Since the male XL^X produces two kinds of sperms, it is 

 apparent that there will be two kinds of daughters produced 

 in each case. In the first case daughter XL2OL1 will be a high 

 producer, because she carries both the ii and L% factors. 

 Daughter XOLi, however, will only be a mediocre producer, 

 because she does not carry the high-producing factor. In 

 the second case, daughter XLiO will be a mediocre producer, 

 because, though she carries Z2, she lacks Li. Daughter XO 

 will be a very poor layer, because she carries neither the 

 factor for a fair or mediocre production (Li), nor the factor 

 for high production (Li). 



In this connection it must be imderstood that inasmuch 

 as the male is a non-producer, the only way of finding out 

 whether he carries the X2 factor is through the egg records 

 of his daughters. 



With so much by way of explanation a summary of Pearl's 

 conclusions^ based on studies involving thirteen generations 

 and several thousand fowls may be considered: 



1. "The record of fecundity of a hen taken by and of 

 itself alone gives no definite reliable indication from which 

 the probable egg production of her daughters may be pre- 

 dicted. Furthermore, mass selection on the basis of fecundity 

 records of females alone, even though long continued and 

 stringent in character, failed completely to produce any 

 steady change in type in the direction of selection. 



2. "High fecundity may be inherited by daughters from 

 their sire independent of the dam. This is proved by the 

 numerous cases . . . where the same proportion of 

 daughters of high fecundity are produced by the same sire, 

 whether he is mated with dams of low^ or high fecundity. 



3. " High fecundity is not inherited by daughters from their 

 dam. This is proved by a number of distinct and independent 

 lines of evidence, of which the most important are (o) con- 



1 Maine Bulletin No. 205. 



' "Low fecundity" as used by Dr. Pearl refers to a winter production of 

 below 30 eggs. This term has been widely misunderstood by practical 

 poiiltrymen. It represents the result of the presence of the Li factor and 

 might possibly have been better described as "mediocre fecundity," allowing 

 "low fecundity" to describe, as it seems to have done in the popular mind, 

 the really poor layer that gives no winter production at all. 



