150 MAINE AGRICUIvTURAL EXPERIMENT STATION. I909. 



collateral inheritance of the character "hatching quality of 

 eggs" even though this character is apparently not inherited in 

 the ancestral line. 



At first thought it would seem that there is a contradiction 

 here in saying that there is collateral but not parental inherit- 

 ance. How can sisters be more alike than a random sample of the 

 general population except because of the fact that they are the 

 progeny of the same parents? The contradiction is only appar- 

 ent and not real, however. It has been shown by Pearson * 

 that we may expect to get relatively high coefficients of fra- 

 ternal inheritance associated with low or insignificant parental 

 coefficients, whenever the phenomenon of prepotency in the 

 ancestral line occurs. This is exactly what careful study of 

 the individual records shows to exist in the present material. 

 The point is that the absence of parental correlations with 

 respect to fertility and hatching of eggs shown in Tables XX 

 and XXI does not mean that one of these characters at least 

 (hatching quality) is not inherited. It merely means that the 

 existence of such parental inheritance is masked by the exist- 

 ence of varying degrees of prepotency with reference to this 

 character amongst the mothers. The existence of such prepot- 

 ency is perfectly apparent from (a) the study of individual 

 records, and (b) the correlation between sisters as shown in 

 Table XXVI, in regard to this character. In passing it may be 

 remarked that this case well illustrates the danger of which lies 

 in too hastily drawing conclusions from mass material without 

 careful study of the individual cases. Putting all our material 

 together it leads to the conclusion that the actual fact is that 

 there is a definite inheritance amongst poultry of what has been 

 called in this paper "the hatching quality of eggs." Yet the 

 manner of this inheritance is such that the fact of its existence 

 is entirely obscured in the ordinary parent-ofifspring correlation 

 table compiled to test the question. 



It may be mentioned here, though a detailed discussion of 

 the point is reserved for a future paper, that this phenomenon of 

 sensible fraternal correlations associated with the absence of 

 parental correlation is exactly what is to be expected if the 

 character studied is inherited in a manner similar to that 



* Pearson, K. On the Laws of Inheritance in Man. i. Inherit mce 

 of Physical Characters. Biometrika, Vol. Ii, pp. 357-462, 1903. 



