March 19, 1915] 



SCIENCE 



433 



TABLE 1 



Percentage of Sens Laying and Average Number of Days since Laying for Different Amounts 

 of Yellow in Ear-lohes 



White Leghorns. Total number of reeords, 932; total number of birds, 317 



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 is 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 



be seen that in general as the percentage of 

 yellow increases the egg production falls off, 

 and that the correlation is most marked dur- 

 ing the periods nearest the time when the 

 records were taken. A distinct correlation 

 with color seems to show in the yearly aver- 

 ages but is largely an indirect one. It is gen- 

 erally only the best birds — those that make the 

 large yearly records — that are laying in Octo- 

 ber. Therefore, any method that selects the 

 laying birds at this season will select at the 

 same time the birds laying above average 



TABLE II 



Average Egg Becords for Different Amounts of Yellow in Ear-lohes of 312 White Leghorns 



the 5-10 per cent, color grade, which show an 

 average of only 0.4 days since laying, the num- 

 ber of days increases consistently with the 

 amount of yellow in the ear-lobes. The per- 

 centage of records that indicate actual laying 

 drops rapidly from 87.8 per cent, for 5-10 per 

 cent, yellow to zero for grades of yellow above 

 30 per cent. The three cases of laying among 

 records above 30 per cent, yellow were for 

 sporadic layers. The table shows that it is 

 practically certain that a bird with an ear-lobe 

 showing more than 30 per cent, yellow at the 

 time of the records is not in a laying condi- 

 tion. 



Table H. shows the percentage of yellow in 

 the ear-lobes of 312 birds according to the 

 color records of October 20, together with egg 

 records for the different color groups. It will 



throughout the year, and consequently 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 production for the months of Sep- 

 tember and October and also above 30 per cent, 

 yellow the yearly totals fall to between 130 and 

 140 with but slight change thereafter. 



By the use of beak and leg color, similar 

 results to those shown in Tables I. and II. 

 have been worked out for other breeds than 

 Leghorns and more complete data are being 

 published elsewhere. 



The data presented indicate a connection 

 between the amount of yellow pigment show- 

 ing in a hen and her previous laying activity. 

 The most natural assumption is that laying 

 removes yellow pigment with the yolks more 



