302 



THE AMERICAN NATURALIST 



[Vol. XLIX 



possible are handled exactly alike. 7 The influence of 

 different environmental factors, therefore, can be largely 

 neglected. 



A preliminary test was made the middle of last Septem- 

 ber by taking from each of a number of different pens a 

 pair of birds representing the extremes of yellow pig- 

 mentation and comparing their egg records. This test 

 indicated that the extremely pale birds were laying and 

 the extremely yellow ones were not. It indicated also that 

 the car lobes were much more easily graded as to color 

 and in addition were apparently more indicative of egg- 

 laying activity than the beaks and legs. The ear-lobes of 

 the American breeds are red like the comb and wattles and 

 do not show yellow pigment. The ear-lobes of certain 

 other breeds, like the Blue Andalusians, are white but 

 apparently remain without any appearance of yellow ever 

 taking place. The Leghorns, including Browns, Blacks, 

 Buffs and Whites, show marked changes in the amount of 

 yellow in their ear-lobes. White Leghorns, of which 

 there were over 300 in the contest, were accordingly 

 chosen for closer study. 



Ear-lobe Color in White Leghorns— Color can be con- 

 veniently measured quantitatively by means of the Milton 

 Bradley color top, which, when spinning, acts as a color 

 mixer. Tn matching ear-lobes, only yellow and white 

 sectors have been used. The matching is not perfect, 

 especially in the lower grades, since a certain amount of 

 bluish tinge is often present. The amount of yellow, how- 

 ever, has probably been more accurately measured than 

 if the other color components were considered. By the 

 method used, it appears possible under proper illumina- 

 tion for one to repeat readings with a change of seldom 

 more than 5 per cent, yellow above or below the mean 

 observation. 



Top readings were taken of the White Leghorns listed 



» Four pens of White Leghorns and four of White Rocks, belonging to the 

 Experiment Station, had sour milk substituted for different ingredients of 



