obesity results.

The elasticity of the skin is another quality that varies with the
concentration in the blood of the internal secretions. Elasticity of
the skin, its recoil upon being stretched like a rubber band, may be
taken as a measure of the activity of all the endocrine glands. For,
as can be noticed especially upon the back of the hand, the older a
man grows, the less elastic becomes the skin. In older people, raising
the skin upon the back of the hand will cause it to stand up as a
ridge for a few seconds and then slowly to return to the level of the
surrounding skin. Whereas in a youthful person it will quickly snap
back into place. This quality of elasticity of the skin is due to the
presence in it of the so-called yellow elastic fibres, cell products,
with a resilience greater than anything devised by man. The
preservation of the resilience is a function of the internal
secretions. Thus, after loss of the thyroid, the ridging effect
characteristic of senility can be produced in one young as measured by
his years. It has been said that a man is as old as his arteries, and
also that as he is as old as his skin. It might better be said that he
is as old as his elastic tissue, young when he is rich in it, old when
poor and losing it. And as elastic tissue and internal secretions
stand in the relation of created and creators, or at least preserved
and preservers, a man may be said to be as old, that is as young,
fresh and active as his ductless glands.

THE HAIR

There is no characteristic of the human body, except perhaps
the teeth, more influenced in its quality, texture, amount and
distribution than the hair. And again, each of the glands of internal
secretion plays a part, but most importantly the thyroid, the
suprarenal cortex and the interstitial sex glands. All contribute
their specific effect, and the blend, the sum of the additions and
subtractions constituting their influences, appears as a specific
trait of the individual, a trait so significant as to be used by the
professionals absorbed in the study of man, the anthropologists, as a
criterion of racial classifications.

Some acquaintance with the history of the normal growth of hair is
necessary to its understanding. There develops during the life of the
fetus within the womb a curious sort of wooly hair everywhere over
the entire body (excepting the palms and soles which remain hairless
throughout life), remarkably soft and fluttery--the lanu