Abstract EARLY work of Palmer and Kempster (1919 a, b) indicated that no carotinoid pigment other than that in the feed was deposited in the yolk. Some pigment continued to be deposited in the yolks from hens on a diet of extremely low carotinoid content. These workers concluded that such residual pigment was not carotinoid in nature and the quantity was not reduced by long continued feeding of carotinoid free diets. The carotinoid-bearing yellow yolk is deposited in a period of seven to ten days just prior to ovulation, Riddle (1916), Romanoff (1931), Marza and Marza (1935), and Warren and Conrad (1939). If the conclusion of Palmer and Kempster is correct, hens raised on high and low carotinoid diets would lay eggs of identical carotinoid content after 11 or more days of low carotinoid feeding. The carotinoid pigments absorb light at wave length 3250A which interferes with spectrophotometric determination of vitamin . . .