lk and white
differ widely in composition. The yolk contains a much larger per cent
of solids than the white, and is rich in both fat and protein, from a
third to a half of the weight being fat. The white has about the same
amount of water, 88 per cent, as average milk, but, unlike milk, the dry
matter is mainly albumin. The entire egg (edible portion) contains
about equal parts of fat and protein; 12 to 13 per cent of each and an
appreciably large amount of ash or mineral matter,--from 0.8 to 1 per
cent, consisting mainly of phosphates associated with the albumin. There
is no material difference in chemical composition between white and dark
shelled eggs, or between eggs with different colored yolks. It is simply
a question of coloring matter. The egg is influenced to an appreciable
extent by feed and general care of the fowls. The egg and the potato
contain about the same amount of water. They are, however, distinct
types of food, the potato being largely composed of carbohydrates and
the egg of protein and fat. Eggs resemble meat somewhat in general
composition, although they contain rather less of protein and fat. When
eggs are boiled there is a loss of weight due to elimination of water;
otherwise the composition is unaltered, the coagulation of the albumin,
as stated in Chapter I, consisting simply in a rearrangement of the
atoms of the molecule. The egg is particularly valuable in the dietary
of the convalescent, when it is desired to secure the maximum amount of
phosphorus in organic combination.

[Illustration: FIG. 30.--GRAPHIC COMPOSITION OF AN EGG.]

The flavor of eggs is in part due to the food supplied to the fowls, as
well as the age of the egg. Experiments show that onions and some other
vegetables, when fed to fowls, impart odors and taste to the eggs. The
keeping qualities of eggs are also dependent upon the food supplied. In
experiments at the Cornell Experiment Station, when hens were fed on a
narrow, nitrogenous ration, a large number of eggs were produced
containing the minimum amount of solid matter and of poor keeping
quality, while a larger sized egg of better keeping quality was obtained
when a variety of foods, nitrogenous and non-nitrogenous, was supplied.

140. Digestibility of Eggs.--Digestion experiments show that there is
but little difference in the digestibility of eggs cooked in different
ways. A noticeable difference, however, is observed in the rapidity with
which the albumin and p