78 COLOR FEEDING 



as soon as the dye was withheld. Whereas the fowl fed Saffranine Red 

 steadily put on weight as long as the dye was given. 



THE EGG 



The eggs from the fowls fed Sudan III had as before stated, yolks of a 

 bright red color (Plate I, C). The density of this color, however, varied 

 with the amounts fed and the frequency of the feedings. Daily feeds pro- 

 duced concentric layers of red alternating with yellow yolk. Even with 

 the dye in all the food given no uniformly colored yolks were produced. The 

 eggs laid soon after the first feeding of dye were banded near the outer part 

 only. These two facts show that the yolk is built up by successive layers of 

 fat deposited on the surface of the material already present and is not made 

 by any intermingling of materials deposited at different times. 



When the color was fed at stated intervals, the rate of growth within the 

 yolk was obtained. It is not only possible, in this way, to calculate the 

 number of days required to completely develop the yolk, but also to study 

 the relative amount of material added during the stages of its formation. 

 We find that the deposition of yolk material is very slow at first but exceed- 

 ingly rapid later, the outer bands being much broader as well as greater 

 in circumference. With a particular fowl observed it required fourteen 

 days for the yolk to be fully formed. This observation was taken during 

 the heavy laying season. 



It was apparent that the color bands were much thinner than the yellow 

 bands of yolk when the dye was fed daily. This would indicate that the 

 colored food from each feeding remained in the blood less than one-half day 

 about eight hours, according to the relative thickness of the bands. 

 Even when all of the food was colored, the yolk deposits varied in density of 

 color. An explanation of this condition might be that the rate of deposition 

 of the fat and albumen vary during the day and night and that while one is 

 being deposited heavily, the other is less abundant. 



The germ disc, albuminous center and connecting tube were left un- 

 colored, showing that either they contain little or no fat or were a part of 

 the ovary before the dye was fed. Plate I, C indicates the position of the 

 white yolk center, the germinal disc and the white connecting tube. It 

 can be observed also that the yolk layers do not break evenly at the tube 

 but have an upward bend toward the germinal disc. 



The Rhodamine Red dye colors principally the albumen of the egg. 

 There is not enough protein in the yolk to make the color show very 

 distinctly in contrast to the yellow. The albumen is colored uniformly 

 throughout Plate I, A, but the density of the color often varies from day to 



