INHERITANCE OF FECUNDITY IN DOMESTIC FOWE. 305 



high fecundity. The presence of this factor will be denoted by 

 L2 and its absence by h. When F and Li are present the addi- 

 tion of L2 makes a winter production of over 30 eggs. If F is 

 present and L^ absent (L) the presence of L2 leads to a winter 

 production of under 30 eggs. Thus either Li or L^ alone makes 

 a record of 30 eggs. They are independent determiners of this 

 degree of production. It should be pointed out, however, that 

 in spite, of their equivalence in this regard, the factors L^ and 

 L2 are not qualitatively the same. That is, the increased pro- 

 duction when 1,1 and L- are both present, is not because there 

 are present two 'doses" of the same determiner. The proof of 

 this is found in the fact that when there are two 'doses' of Li 

 present in a bird it does not make her a high producer. Li may 

 be considered an excess production factor, which erects a super- 

 structure on the foundation furnished by Lk In the absence of 

 L\ 1/2 lacks the foundation from which to start and hence only 

 can build about as high as Li would alone. One /-.i cannot, how- 

 ever, build a superstructure on another Li] nor can an Fz build 

 one on another F-^. Of course it will be understood that with / 

 (absence of female sex and ovary) these physiological fecundity 

 factors /yi and Fi are simply latent. 



Using the letters in the manner defined above, and with the 

 usual Mendelian method of writing gametic and zygotic formu- 

 lae, the data indicate the existence of Barred Plymouth Rock 

 and Cornish Indian Game m.ales and females of the constitu- 

 tions set forth below. The only point needing particular atten- 

 tion in reference to these formulae is that the factor L-^ behaves 

 in inheritance as a sex-limited character precisely like the 

 barred color pattern of the Barred Rock (40, 41). In conse- 

 quence gametes of the type FF2 are never formed. Any gamete 

 which bears F does not, under any circumstances, ever carry L^. 



It is not desirable to take the space to consider here all the 

 consequences which flow from the circumstance of the high fe- 

 cundity factor L2 being a sex-limited character. These matters 

 will be fully discussed farther on in the paper after the data 

 tuemseives have been presented. Here it need only be said that 

 since F2 is a sex-limited character corresponding in behavior to 

 the barred color pattern, it means that $ $ may be formed with 

 any combination of the factors Li and La, whereas ? 9 which 

 bear Li at all, must be h^'terozygotic in respect to it. Females 



