104 Maine; agriculturaIv e^xperiment station. 1910. 



differences. These differences consist of (a) a markedly lower 

 mean winter production in the Cornish than in the Barred 

 Rocks and (b) a markedly greater relative variability as meas- 

 ured by the coefficient of variation in winter egg production in 

 the Cornish. 



3. The hybrid pullets are seen to fall into two distinct classes 

 in respect to egg production. The barred hybrid pullets coming 

 from the mating Barred Rock J* x Cornish 5 are good winter 

 layers, having about the same mean production as the pure 

 Barred Rocks. The black hybrids, on the other hand, which 

 come from the mating Cornish J^ x Barred Rock 5 are relatively 

 poor layers, with a mean winter production more than 11 eggs 

 lower than that of the barred hybrids. In other words, the 

 hybrid pullets whose mothers were good layers are themselves 

 poor layers, while those whose mothers were poor layers are 

 themselves good layers. Cpuld any more striking evidence be 

 adduced to show that the egg record of the mother, in and of 

 itself alone, is a poor indication of what her daughter is likely 

 to lay? Furthermore, the barred hybrids show about the same 

 degree of relative variability in egg production as the pure 

 Barred Rocks, whereas the black hybrids show a much higher 

 relative variability, comparable with that of the Cornish. 



These results stated under paragraph 3 are very clear cut and 

 definite, as a study of tables 10 and 11 will demonstrate. 

 They are of much interest, both theoretical and practical. 

 They show that winter egg producing ability is inherited in 

 these hybrids in a manner essentially like that in which the 

 barred plumage pattern is inherited, as described above (pp. 

 87-89). The behavior of egg productivity in these hybrids is 

 precisely of the kind we should expect to get if it were a "unit 

 character" (i. e., a definitely segregable character) in the Men- 

 delian sense. The facts in hand suggest, though of course they 

 do not prove, that egg productivity is inherited in a sex limited 

 manner, as is barring and shank color (cf. pp. 87 and 107). 



The results respecting egg production in these hybrids sug- 

 gest the Mendelian interpretation given below. Before detail- 

 ing this particular interpretation it is desired to set forth our 

 position regarding such interpretations in general. It is our 

 opinion, subject of course to modification in the light of com- 

 pelling facts if such appear, that the purely morphological con- 

 ception of inheritance which is implied in much of Weisman- 



