PLATE 1 
EXPLANATION OF FIGURES 
All figures natural size. 1-6 and la-6a represent series of ezgs grown simultane- 
ously in two Sudan-fed hens. About 20 milligrams of Sudan fed to each hen at, 
2p.M., January 27, and at 10 a.m., January 30 (sixty-eight hours). 
The bird bearing series la—6a killed February 2, 10 a.m. (70 hours after last Sudan 
began to be deposited in yolk). 
1 Egg laid January 27, with pear-shaped, more solid ‘waxy’ interior; also two 
prominent circles of ‘modified yolk’ near periphery. 
2 Egg laid January 29. The outer border line here represents Sudan deposited 
from feeding of January 27. This layer was 1 mm. in thickness. The two cir- 
cles of ‘modified yolk’ showing here as in figs. 1, 3 and 4. The size of each of the 
yolks at the time of the modification is indicated by these circles. 
3 Egg laid January 31; see above. 
4 Egg laid February 2. Two layersof Sudan. Thetime between Sudan feedings 
was sixty-eight hours; the amount of yolk deposited in this egg during that time 
was 6.2mm, = 2. 2. mm. in twenty-four hours. Section nearly in plane of germ. 
5 Egg laid February 4. The two layers of Sudan here as in fig. 4, were 6.2 
mm. apart = growth of 2.2 mm. in twenty-four hours. Section at right angles 
to plane of germ. 
6 Egg laid February 7. Shows spreading, or dilation, effects in Sudan layers. 
Apparently the ‘spreading’ is mostly outwards, though this figure well repre- 
sents neither the position nor the condition of each layer. This effect noted in eggs 
that have remained long in ovary, or, as in this case, in laboratory at high tem- 
peratures. 
la Egg laid January 27. To unaided eye the outer 10 mm. of one side of this 
egg showed very plainly six pairs of yolk layers = 1.67 mm. each. Interior con- 
tained somewhat solid, waxy body 15 X 10 mm. 
2a Egg laid January 29. Seven very distinct pairs of layers of white and yellow 
yolk. The white yolk represented by dotted lines; the yellow yolk by the spaces 
between these. Probably another layer central to those indicated in figure. 
3a Hgg 40 X 27 X 28 taken from oviduct (see first statement above). Inner 
borders of two Sudan layers are 4 mm. apart = 1.41 mm. growth per twenty- 
four hours. Section through plane of germ. 
4a Egg 31 X 26 X 28 from ovary (February 2). Distance between inner borders 
of Sudan lines = 3.6mm. = 1.3mm. intwenty-four hours. Section nearly in plane 
of germ. Figs. 3a and 4a show the spreading or diffusion of Sudan in the region of 
the germ. Distance between inner border of outer Sudan layer and periphery = 
5.mm.; this growth of seventy hours = growth of 1.7 mm. in twenty-four hours. 
5a Egg 24 X 21 X 20, from ovary (February 2). The first feeding of Sudan 
(January 27) left but faint traces of the dye in this small egg (see small crescent). 
By mistake the inner border of the thick layer of Sudan of this figure was placed 7 
mm. from periphery instead of 5 as it actually was. This 5 mm. = growth of 
seventy hours = 1.7 mm. growth in twenty-four hours. 
6a Egg 15 X 16 X 19, from ovary (February 2). Smallest egg in which trace of 
Sudan was present; this somewhat diffuse and indicated by dotted circle. From 
inner border of circle to periphery = 4.8 mm. the growth of seventy hours = 1.64 
mm. growth in twenty-four hours. 
All eggs are drawn as perfect circles, although, as is indicated above, the boiled 
yolks quite constantly show three unequal diameters. 
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