THE BREEDING OF CHICKENS 145 



which the inheritance of fecundity is hraited, is found in tlie 

 color of the Barred Plymouth Itock. It is a matter of com- 

 mon observation tliat the Plymouth Rock males are always of 

 a lighter shade than the females. This comes about through 

 the fact that the females inherit the lig'ht bars from their 

 sires only and never from their dams, whereas the males 

 always inherit light barring from both sire and dam, thereby 

 receiving a double dose of the light barring. 



The reason for this appears to lie in the fact that hens 

 produce two kinds of eggs, one of which when fertilized, 

 always produces males, while the other produces females. 

 The male j)rodnces only one kind of s[)erm so far as sex is 

 concerned, and these all carry the factor for barring. The 

 female-producing eggs never carry the barring factor, while 

 the male-producing eggs always do. The only result pcissible 

 is that the mair inherits light barring from l>i)th his sire 

 and dam, while the female inherits it only from her sire. 



A summary of Pearl's conclusions' are as follows: 



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 tlie 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 (a) con- 



' 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 

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

 might possibly ha^'e 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. 

 10 



