This section is from the book "Elements Of The Theory And Practice Of Cookery", by Mary E. Williams. Also available from Amazon: Elements Of The Theory And Practice Of Cookery; A Textbook Of Domestic Science For Use In Schools.
A hen's egg consists of shell, two layers of white, yolk, and two membranes, one a silky skin between shell and white, the other, so thin as to be invisible, between white and yolk. Two twisted cords of white extending from this inner membrane hold the yolk in place. The little mass in the yolk is the embryo from which the chicken grows, just as the seedling grows from the embryo of the seed. The contents of the egg, like the seed-contents, nourish the developing embryo; when ready to be hatched, the chick has absorbed all of these contents, and part of the shell. The egg is a perfect food for an unhatched chicken, as starch is for a seedling.
Eggs should have hard shells and deep yellow yolks. The color of the shell does not matter. For the wholesale market, eggs are sorted and small eggs bring a lower price. Fresh eggs have a delicate flavor and almost no odor. The white and yolk are distinct and easily separated.