Full text: Problems in eugenics

8Section I.R. Pearl’ 
where the new being is organised. Now, this contest does not take 
place en bloc, so to speak, as has been generally admitted. Each of 
the characters of the two parents struggles on its own account against 
the corresponding character (its antagonist, as has just been said). 
When the hereditary energy is equal on both sides there necessarily 
ensues a kind of process of which the consequence is the fusion of the 
maternal and paternal characters in an intermediate character. If the 
energies are very unequal the hybrid inherits a character borrowed 
entirely from one of his parents; but this parent, conqueror on one 
point, may be conquered upon another. Hence, there results with the 
hybrid a juxtaposition of characters derived from each of the types of 
which he is the child.” 
Above all, I have wished to call attention to the so-called laws of domin­ 
ance, because of their great importance. We may conclude that in the case 
of man the dominant characters are also the original ones. 
THE INHERITANCE OF FECUNDITY. 
(Abstract.) 
By Raymond Pearl, 
Biologist, Maine Agricultural Experiment Station. 
The purpose of this paper is to give an account (necessarily abbreviated, 
and without presentation of complete evidence) of the results of an 
investigation into the mode of inheritance of fecundity in the domestic fowl, 
and to point out some of the possible eugenic bearings of these results. 
It is shown that while the continued selection, over a period of years, 
of highly fecund females failed to bring about any change in average 
fecundity of the strain used, this character must nevertheless be inherited 
since pedigree lines have been isolated which uniformly breed true to definite 
degrees of fecundity. 
It is further shown that observed variations in actually realized fecundity 
(number of eggs laid) do not depend upon anatomical differences in respect 
to the number of visible oocytes in the ovary. The differential factor on 
which the variations in fecundity depend must be primarily physiological. 
Fecundity in the fowl is shown to be inherited in strict accord with the 
following Mendelian plan :— 
1. Observed individual variations in fecundity depend essentially upon 
two separately inherited physiological factors (designated Lx and L2). 
2. High fecundity is manifested only when both of these factors are 
present together in the same individual.
	        

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