3f>4 



THE AMERICAN NATURALIST [Vol. XLIX 



of 312 birds according to the records of October 19-21, 

 together with monthly and yearly egg records for the 

 different color groups. The months of October and Sep- 

 tember are each divided into halves. It will be seen that 

 in general as the percentage of yellow increases, the egg 

 production falls off, and that the correlation is most 

 marked during the periods nearest the time when the 

 records were taken. A distinct though slight correlation 

 seems to show as far back even as July and is strikingly 

 evident in the yearly averages. For months before Sep- 

 tember and October, the correlation with color is probably 

 an indirect one. It is generally only the best birds — those 

 that make the large yearly records — that are laying in 

 October. Therefore, any method that selects the laying 

 birds at this season will select, at the same time, the birds 

 laying above average throughout the year and conse- 

 quently give high yearly totals. It will be observed that 

 30 per cent, seems to be a critical amount of yellow. 

 Above this amount comes the sudden drop in egg produc- 

 tion for the months of September and October and also 

 above 30 per cent, yellow the yearly totals fall to between 

 l."»n an«l 140, with hut -light change thereafter. 



In Table II, the records at the three different readings 

 have been used. A bird laying on the day of record or on 

 a later day within the month is considered to be laying and 

 credited with a zero. If she laid on the day before the 

 record but not later, she is credited with one "day since 

 laying," and in a similar way a longer period of inactivity 

 in laying is indicated by a larger number of days since 

 laying. With the exception of a few cases where this was 

 not possible, three records were taken of each bird. Since 

 October is the season of decreasing egg production, the 

 majority of the birds increased their quantum of yellow 

 and consequently most birds are listed in more than a 

 single color grade. Beginning with the 41 records in the 

 5-10 per cent, color grade which show an average of only 

 0.4 day since laying, the number of days increases con- 

 sistently with the amount of yellow in the ear-lobes, the 

 irregularity at 70 per cent, being probably due to the 



