tropisms, in which man is pushed and pulled about in his environment as are iron filings in a magnetic field.  Think up objective physiologies in which your life and mine become a series of concatenated influences and compound reflexes.  Play with words like the concentration reflex when you mean idea, and the symbolic reflex when you mean language.  But your most rigid nomenclature will never abolish the mystic personal purpose in the equation, no matter how low the step in the animal series to which you descend.  The declaration that a man is dominated by certain glands within his body should not be taken to give aid and comfort to those who would banish mind from the universe.

CHAPTER I

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 were poured out upon some surface of the body.  Either an exterior surface like the skin, or some interior surface, the various mucous membranes.  This was supported by the discovery of canal-like passage ways leading from the gland to the particular surface where its secretion was to act.  These corridors, the secretory or excretory ducts, are present, for example, in the liver, conducting the bile to the small intestine.  Devices of transportation fit happily into a comparison of a gland to a chemical factory, corresponding thus closely to the tramways and railroads of our industrial centers.

Little more than a hundred years ago, it was observed that certain organs, like the thyroid body in the neck, and the adrenal capsules in the abdomen, hitherto neglected because their function was hopelessly obscure, had a glandular structure.  As in so much scientific advance, the discovery or improvement of a new instrument or method, a fresh tool of research, was responsible.  The perfection of the microscope was the reason this time.