BREEDINO 139 



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

 produce two kinds of ova, one of which always produces 

 males when fertilized, while the other produces females. 

 The male produces only one kind of sperm so far as sex is 

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

 female-producing ova never carry the barring factor, while 

 the male-producing ova always do. The only result possible 

 is that the male inherits light barring from both his sire 

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



Fig. 69 



Showing the difference in barring of Plymouth Rocks that are full brother 

 and sister. (Courtesy of Kansas Experiment Station.) 



This may be illustrated as follows : Let X represent an ovum 

 that will produce a male when fertilized by a spermatozoon, 

 which may also be designated by X. Let represent an 

 ovum that will produce a female when fertilized. That is 

 to say, offspring having the constitution XX will be males, 

 while those represented as XO will be females. X always 

 carries a factor for light barring, while never carries such 

 a factor. The mating of a pair of Barred Plymouth Rocks 

 may be represented as follows, if B is allowed to represent 

 the barring factor. 



