464 The Bird 
vorticella, on their queer little corkscrew stems. All these 
are made up of but a single cell, and in the beginning all 
seeds of plants and all eggs of animals likewise consist of 
one cell. 
If we examine a chicken while it is being dressed for the 
table, we can easily find the ovary, a mass of hundreds 
of tiny golden spheres,—eggs which would have been 
laid during the coming years. So we realize that the most 
essential part, in fact the real egg, is only the yolk; all 
else being merely protective. The shell protects the yolk 
while the chick is developing during incubation, and 
although formed of crystals of lime, yet it is so porous 
that oxygen can enter and carbonic acid gas escape. The 
viscid white, or albumen, is nutritious as well as protective, 
while the yolk itself is the real food of the embryo and also 
acts aS a support to the developing chick. If we look 
carefully, we will see two whitish, twisted strands which 
extend from the yolk through the white. These two strands 
have whitish opaque knots strung along them, and from a 
fancied resemblance to hailstones they are called chalaze. 
These act as pads to protect the yolk from sudden jars, 
but they do not act as suspensories. A hen never turns 
her eggs, aS many people imagine, to warm the different 
sides equally, for the germ-dot—the position of the future 
embryo (of which we will speak presently)—is always 
on the lightest side of the yolk, and whichever way the egg 
is turned it always swings uppermost, nearest the heat 
from the body of the sitting hen. The turning, however, 
may be of advantage in allowing moisture to act upon a 
greater surface of shell. 
