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THE AMERICAN NATURALIST [Vol. XLIX 



The method of grading beak and leg color may appear 

 crude, but that it is capable of giving valuable evidence of 

 previous laying activity is further shown by data kindly 

 turned over to us by Professor C. A. Wheeler. On Octo- 

 ber 26, 1912, under his direction a series of measurements 

 of 132 White Leghorns from the contest was taken by Mr. 

 E. E. Jones. Among other records, the ear-lobes were 

 graded as white, cream or yellow and the legs as pale or 

 yellow, but no connection was worked out between the 

 color and the egg records. These 132 birds we find to 

 have a yearly average of 155.1 eggs. The 34 birds with 

 pale legs averaged 188.9 eggs; the 98 with yellow legs, 

 143.5 eggs. The 33 birds with white lobes averaged 190.1, 

 while the 99 with cream or yellow lobes averaged 143.5. 

 The 21 birds that had both white ear-lobes and pale legs 

 averaged exactly 200 eggs. 



The data presented in the foregoing pages indicate a 

 connection between the amount of yellow pigment showing 

 in a hen and her previous laying activity. The most nat- 

 ural assumption is that laying removes yellow pigment 

 with the yolks more rapidly than it can be replaced by 

 the normal metabolism, and in consequence the ear- 

 lobes, the beak and the legs become pale by this subtrac- 

 tion of pigment. 



Environmental factors, other than laying, may be of 

 more or less influence on yellow pigmentation. In fact, 

 birds obviously sick have been observed to be pale al- 

 though not in a laying condition. In the material investi- 

 gated, however, variation in the laying activity seems to 

 be the prime cause of the changes in yellow pigmentation 

 in the domestic fowl. 



The data of the present paper have been summarized 

 in a preliminary report in Science, March 19, 1915. Pho- 

 tographs showing differences in yellow pigmentation in 

 fowls are given in an article in the Journal of Heredity, 

 April, 1915. 



The change in yellow pigmentation is being further 

 studied by a twice weekly top record of a flock of birds 

 throughout the year. 



