e muscle tubes and the character of the
connective tissues which bind the tubes and muscles together. In
young and well-nourished animals the tube walls are thin and
delicate, and the connective tissue is small in amount. As the
animals grow older or are made to work (and this is particularly
true in the case of poorly nourished animals), the walls of the
muscle tubes and the connective tissues become thick and hard. This
is the reason why the flesh of young, well-fed animals is tender
and easily masticated, while the flesh of old, hard-worked, or
poorly fed animals is often so tough that prolonged boiling or
roasting seems to have but little effect on it.

"After slaughtering, meats undergo marked changes in texture. These
changes can be grouped under three classes or stages. In the first
stage, when the meat is just slaughtered, the flesh is soft, juicy,
and quite tender. In the next stage the flesh stiffens and the meat
becomes hard and tough. This condition is known as _rigor mortis,_
and continues until the third stage, when the first changes of
decomposition set in. In hot climates the meat is commonly eaten in
either the first or second stage. In cold climates it is seldom
eaten before the second stage, and generally, in order to lessen
the toughness, it is allowed to enter the third stage, when it
becomes soft and tender, and acquires added flavor. The softening
is due in part to the formation of lactic acid, which acts upon the
connective tissue. The same effect may be produced, though more
rapidly, by macerating the meat with weak vinegar. Meat is
sometimes made tender by cutting the flesh into thin slices and
pounding it across the cut ends until the fibers are broken."

135. Influence of Cooking upon the Composition of Meats.[47]--It is
believed by many that losses are prevented and the nutritive value
conserved when, in the cooking of meat, it is placed directly into
boiling water rather than into cold water and then brought to the
boiling point and cooked. Extensive experiments have been made by Dr.
Grindley in regard to this and other points connected with the cooking
of meats, and in general it was found that the temperature of the water
in which the meat was placed made little difference in its nutritive
value or the amount of material extracted. It was found that by both
me