EGG PRODUCTION. 59 



of mothers what would have been the average egg production 

 of the daughters for the whole year? This can be determined by 

 adding 86.9, the mothers' average production from June i to 

 November i, to 61.9, the daughters' production from November 

 I to June I. In this way one gets 148.8 eggs as the average 

 production of the daughters for the whole year, had they been 

 allowed to make a record for the year and assumed to lay as 

 well as the mothers during the summer and fall months. 



In considering this result two things must be kept in mind. 

 In the first place the assumption that if the daughters had been 

 allowed to continue their records they would have laid on the 

 average as well as the mothers during the summer months is, 

 from the standpoint of actual experience, an absurd one. This 

 is probably sufficiently evident on general grounds, but we 

 further have definite mathematical evidence of it. It is not 

 possible to take space to present this evidence in detail here, 

 but in a word it consists in the fact that the egg production at 

 any one part of the year has been found to be positively corre- 

 lated with that of any other part of the year. That is, it has 

 been found on the basis of the 9 years trap nest records at this 

 Station that on the average the bird which is an unusually good 

 layer at one period of the year will also have an unusually good 

 egg production record for any other portion of the year what- 

 soever and vice versa. The poor winter layer does not on the 

 average, and in the long run make the good summer layer, 

 though this is often assumed to be the case. 



In the second place it is clear enough that, even if the truth 

 of the assumption that the daughters would have laid as well as 

 the mothers during the summer could be granted, the daughters' 

 average would still be more than 50 eggs lower for the year 

 than the mothers'. No further comment on this point seems 

 necessary. 



(2) So far there have been considered only the results when 

 the records are broken up into winter and spring laying periods. 

 It is perhaps well to examine the figures for the whole period 

 over which we have data, namely, from November i to July i 

 of the inillct year. Comparing mothers and daughters in regard 

 to egg production over this period ftwo-thirds of the year) we 

 have the results shown in Table II. 



