HOW THE GLANDS OF INTERNAL SECRETION WERE DISCOVERED


Just what are the glands of internal secretion? And how have we become
possessed of whatever information about them we have? A brief review
of how the idea of a gland of internal secretion came into the human
mind and of the contributions that have converged into a single body
of knowledge is worth while.

A gland is a collection of cells (those viscous globules which are the
units of all tissues and organs). It manufactures substances intended
for a particular effect upon the body economy. The effect may be
either local or upon the body as a whole.

Originally, a gland meant something in the body which was seen to make
something else, generally a juice or a liquid mixture of some sort.
A classical example is the salivary glands elaborating saliva. The
microscope has shown us that every gland is a chemical factory in
which the cells are the workers. The product of the gland work is its
secretion. Thus the sweat glands of the skin secrete the perspiration
as their secretion, the lachrymal glands of the eyes the tears as
theirs. The collectivism of management and control is the only
essential difference between them and the modern soap factory or
T.N.T. plant.

Man as a carnivor, and as a consequent anatomist, has been acquainted
with these more superficially placed glands for some thousands of
years. During all this time and during the epoch of the achievements
of gross anatomy, it was believed that the secretions of all glands