INHERITANCE OF THE FUNCTION OF EGG PRODUCTION 



IN THE DOMESTIC FOWL AND ITS INFLUENCE ON THE 



FERTILITY AND HATCHING POWER OF EGGS 



BY RAYMOND PEARL 



Introductory Note 



The address which was given under the above title was based upon 

 investigations which have been reported in two papers. That portion of 

 the address which dealt with the inheritance of egg producing capacity 

 sensu strictu is discussed in a paper which was given before the American 

 Society of Naturalists in 1910 and is here reprinted in full. That portion 

 which dealt with the results then in hand respecting the inheritance 

 of the fertility and hatching power of eggs has been printed as Bulletin 

 168 of the Maine Agricultural Experiment Station, with the title "Data 

 on Certain Factors Influencing the Fertility and Hatching of Eggs." Since 

 this material is, and has been for some time, available to the members of 

 the Association there is no reason for reprinting it in whole or in part here. 



The paper which follows was originally published in the American 

 Naturalist, Vol. XLV, pp. 321-345, June, 1911. 



INHERITANCE OF FECUNDITY IN THE DOMESTIC FOWL 1 



There are under discussion at the present time two general views regard- 

 ing certain fundamental points in heredity. Each of these points of view 

 has its zealous adherents. On the one hand, is what may be designated 

 the "statistical" concept of inheritance, and on the other hand, the concept 

 of genotypes. By the "statistical" concept of inheritance is meant that 

 point of view which assumes, either by direct assertion or by implication, 

 that all variations are of equal hereditary significance and consequently 

 may be treated statistically as a homogeneous mass, provided only that they 

 conform to purely statistical canons of homogeneity. This assumption of 

 equal hereditary significance for all variations is tacitly made in deducing 

 the law of ancestral inheritance, when individuals are lumped together in a 

 gross correlation table. 2 The genotype concept, on the other hand, takes as 

 a fundamental postulate, firmly grounded on the basis of breeding ex- 



1 Papers from the Biological Laboratory of the Maine Experiment Station, No. 25, 

 This paper was read at the meeting of the American Society of Naturalists at Ithaca. 

 December, 1910. 



2 For a more detailed discussion of this point see a paper by the present writer 

 entitled "Biometric Ideas and Methods in Biology; their Significance and Limitations," 

 in the Revista di Scienza (in press). 



