ic contraction of the muscles. A small glandular organ at the
base of the brain, the pituitary body, produces a secretion, one of
the most marked properties of which is a control of growth,
particularly that of the bones. Most cases of giantism, combined as
they are with imperfect mentality, are due to disease of this gland.
There are glands near the kidney which regulate the pressure of the
blood in the arteries by causing contraction of their muscular walls.
The sexual characteristics in the male and female are due to an
internal secretion produced by the respective sexual glands which
affects growth, body development and mentality.

So is the body constituted. A series of surfaces, all connected, of
enormous size, which enclose a large number of organs and tissues, the
activities of which differ, but all are cooerdinated to serve the
purposes of the organism as a whole. We should think of the body not
as an assemblage of more or less independent entities, but as a single
organism in which all parts are firmly knit together both in structure
and in function, as are the components of a single cell.

FOOTNOTES:
[1] They do, however, take place, since within comparatively
few years whole species have completely disappeared; for example, the
great auk and the passenger pigeon. In these cases it is not known
what part disease played in the destruction.

[2] A tissue represents an aggregate of similar cells with
the intercellular substances in relation with these as connective
tissue, muscular tissue, etc. Where such cell aggregates are localized
and where the cells are arranged in structures having definite form
and size and performing a definite function, it is customary to
designate such structures as organs, as the brain, liver, etc.

CHAPTER II

NO SHARP LINE OF DEMARKATION BETWEEN HEALTH AND DISEASE.--THE
FUNCTIONAL NUTRITIVE AND FORMATIVE ACTIVITIES OF CELLS.--DESTRUCTION
AND REPAIR CONSTANT PROCESSES IN LIVING MATTER.--INJURIES TO THE
BODY.--THE EFFECT OF HEAT.--THE ACTION OF POISONS.--THE LESIONS OF
DISEASE.--REPAIR.--THE LAWS GOVERNING REPAIR.--RELATION OF REPAIR TO
COMPLEXITY OF STRUCTURE AND AGE.--THE RESERVE FORCE OF THE BODY.--
COMPENSATORY PROCESSES IN THE BODY.--OLD AGE.--THE DIMINUTION OF
RESISTANCE TO THE EFFECT OF THE ENVIRONMENT A PROMINENT FACTOR IN OLD
AGE.--DEATH.--HOW BROUGHT ABOUT.--CHANGES IN THE BODY AFTER DEATH.--
THE RECOGNITION OF DEATH.

There is no sharp line separating health