PLATE 2 
EXPLANATION OF FIGURES 
Figures all drawn twice natural size, and then reduced one-sixth. 
1 Section at right angles to germ of an egg( 32 X 30 X 28) that showed with 
schematic clearness its rate of growth. The Sudan deposited in the first (inner) 
broken line was fed forty-eight hours before a following feeding. Thereafter the 
feedings of the dye were made at thirty-six hour intervals. A growth of 1.8 mm. per 
twenty-four hours is indicated for the three intervals of thirty-six hours. 
2 Through germ of egg, 33 X 29 X 27. Shows well the manner of deposit of dye 
(and therefore of yolk) in immediate region of germ. The fan-shaped figure of 
dilute Sudan lying deeply beneath the germ is perhaps however not a correct pic- 
ture of the original position of the dye, but a ‘spreading’ effect. The first two feed- 
ings of Sudan were here twenty-four hours apart; the next forty-eight hours and 
the last, twenty-four hours later. A growth of 1.5mm. per twenty-four hours is 
here indicated for time between first and last feedings. 
3 A-series of small ova (4-7.5 mm. in diameter) from the ovary of a laying hen 
which had been once fed about 25 milligrams of Sudan and killed on following day. 
Only three of these ova (6.5 to 7.5mm.) showed any trace of the dye. In the draw- 
ing of the egg of 7.5mm. the position of the layer of dye was placed two mm. too 
near center of egg. The number along side each ovum indicates its actual diameter 
in millimeters. The egg of 7mm. was of special interest. After lying in a quantity 
of Mann’s balanced formalin-alcohol solution for a few weeks the striated appear- 
ance of the outer portion of its white yolk was visible with binocular. The lower 
right hand figure is an attempt to represent the structure of the outer 1.75 mm. of 
the 7mm. egg. Eight strie could be here distinguished. Apparently therefore 
the strie have a thickness of about 0.25 mm. The stain was found to be confined 
to the large, yellow yolk granules. 
4 Egg, 34 X 29 X 31, through plane of germ. Central heavy irregular lines 
are from Sudan feeding three days apart. Bird was laying at long intervals and 
next feeding delayed ten days and following this two feedings two days apart. 
This egg therefore at least seventeen days in developing. But its abnormality is 
evidenced by the crumpled appearance of the innermost layers of Sudan (the cor- 
ners of innermost layer are too sharp in drawing) and by a curious depression of the 
germ. Another peculiarity of this egg was its presentation of a brightly Sudan- 
colored vegetative pole (the stratum of dye here near surface), and a normally 
colored animal pole (except for the small depressed region of germ). 
5 Later egg, sister tono. 4. Much morerapid growth thanin4. First two feed- 
ings thirty-six hours apart; others twenty-four. A growth of 1.3 mm. per twenty- 
four hours is here indicated. 
488 
