586 
PHYSIOLOGY: L. S. PALMER 
the supply of xanthophyll for the skin is cut off by reason of its removal; 
from the food, or for any other reason, any xanthophyll present in the 
corium layer of the skin of the shank, ear lobes, etc., is deposited in the 
rete of Malphigi. At the same time the xanthophyll deposits in the 
outer layer of the epidermis either wear off by reason of the normal 
replacement of the outer cells by those lower down, or are oxidized 
because of closer contact with the air. The xanthophyll deposits in 
the rete of Malphigi in time become a part of the outer layers of epi- 
dermis and are lost also. The skin thus finally becomes free from 
visible yellow pigment. 
The significance of this interpretation at once becomes apparent in 
the light of the results secured when xanthophyll-rich rations were fed to 
the laying carotinoid-free hens. After a month on rations containing, 
an abundance of green feed or yellow corn not a trace of xanthophyll 
had appeared in the ear lobes, shank or vent, and the adipose tissue 
had taken up such a small amount of yellow color that a very careful 
examination of the rendered, melted, body fat was necessary to detect 
the increase in color in comparison with the fat from birds which had 
received no carotinoids in their ration from birth. The blood serum 
and the yolks of the eggs laid during the feeding of the xanthophyll- 
rich rations, however, contained an abundance of yellow pigment. 
As the result of the histological studies and feeding trials the author 
believes that the correct explanation of the physiological relation be- 
tween egg laying and the fading of visible yellow pigmentation from 
the bodies of fowls of certain breeds is that in cockerels and non-laying 
females the visible skin parts represent a normal path of excretion of 
the xanthophyll pigment derived from the food. Egg laying deflects 
the excretion entirely to the ovaries, and even prevents the incor- 
poration of xanthophyll with the tissue fat, and this continues as long 
as the ovaries function with regularity, whether the egg production be 
at the rate of one egg a day or one egg a week. The result is that the 
pigment found in the skin at the onset of fecundity is gradually ex- 
creted toward the epidermis where it either wears away as the result 
of the normal structural changes in the epidermis, or becomes oxidized, 
and thereby decolorized. The movement of yellow skin pigment during 
fecundity is thus outward and not inward toward the ovaries. 
Influence of various feeds and certain dyes on the color of the egg yolk 
and body fat. — ^A critical study was made of the effect of certain coloring 
matters on the pigmentation of adipose tissue, egg yolk and visible 
skin parts, and also of the relative xanthophyll content of various 
