66 Maine; agricui^tural expe;rime;nt station. 1909. 



determining the degree of inheritance of fecundity in this way, 

 to use only famihes in which the number of daughters were 

 equal so that each mother's record would be equally weighted. 



Another possible way of approaching the problem is to enter 

 in the correlation tables only one daughter for each mother. 

 This gets around the weighting of the mothers with their own 

 fecundity but only by involving the further difficulty which 

 arises from the existence of individuality amongst the daughters. 

 This difficulty is easily illustrated. Suppose, in the concrete 

 case under discussion, that some particular mother hen has nine 

 daughters, which one of these daughters shall be taken as the 

 one to have its record entered in the correlation table with the 

 mother's? It is, of course, obvious that, in advance of special 

 investigations of the degree of individuality among daughters 

 in general in regard to egg production, it will be possible to get 

 quite different results from the inheritance of fecundity accord- 

 ing as one picks and chooses the individual daughter to enter 

 into the table by this method. 



On the whole the element of error introduced by weighting 

 mothers with their own fecundity appears to us likely to be less 

 than the error arising from choosing single individual daughters 

 as representative of their families. In view of this considera- 

 tion and of the further fact that this is the method which has 

 been quite generally adopted by students of the inheritance 

 of fecundity it has been decided in the present case to make 

 correlation tables of the sort wherein all daughters (and their 

 mothers) are entered as a first point of approach to the problem, 

 tuch correlation tables for measuring the inheritance of egg 

 production are given in Tables III, IV and V. Qi these tables 

 No. Ill deals with winter (November i to March i) egg pro- 

 duction. No. IV with spring (March i to June i) egg produc- 

 tion and No. V with the total (November i to July i) egg pro- 

 duction. 



It is desirable, for the benefit of those not accustomed to 

 tables of double entry such as these are, to explain and illustrate 

 how such tables are to be read. The figures in the body of the 

 table in each case denote the frequency of occurrence of the pair 

 of events indicated by the marginal classes. To take a concrete 

 illustration from Table III, it will be noted that in the first row 

 and eighth column of the body of the table there is an entry "5." 



