The internal secretions constitute and determine much of the inherited powers of the individual and their development They control physical and mental growth and all the metabolic processes of fundamental importance.  They dominate all the vital functions during the three cycles of life.  They co-operate in an intimate relationship which may be compared to an interlocking directorate.  A derangement of their function, causing an insufficiency of them, an excess, or an abnormality, upsets the entire equilibrium of the body, with transforming effects upon the mind and the organs.  In short, they control human nature, and whoever controls them, controls human nature.

The control of the glands of internal secretion waits upon our knowledge of them, the nature and precise composition of the substances manufactured by them, and just what they do to the cells.  Envisaging the future, that knowledge today is meagre.  Looking back fifty years, it becomes an amazing achievement and revelation.  It is worth our while to survey the accomplished, and to trace its general human significance.  For a certain tangible degree of knowledge and control has been attained and should be part of the average citizen’s equipment in dealing with the everyday problems of his life.

THE ATTITUDE OF THE LABORATORY

A certain number of so-called experimental physiologists, that is, the physiologists of the animal laboratory, who will have nothing but syllogistic deductions and quantitative determinations based upon animal experiments as the data of their science, will be apt to look askance upon the preceding paragraphs, and those which will follow.  To them, any man who relates the internal secretions to anything, outside of the routineer’s paths, puts his reputation at stake, if he has any reputation at all to start in with.  They would have us deliver a Scotch verdict upon all the questions which arise as soon as one attempts to take in the more general significance of the glands of internal secretion.  This, even though the more general implications concerning the effects of their products, the relations of them to growth and development, nutrition and energy, environmental reactions and resistance to disease, as well as the grand complex of intelligence, are admittedly well ascertained in some directions.

The method of absolute measurement in science has yielded miracles.  For some thousands of years, an isolated individual, here and there or an isolated institution have devoted themselves to the task, struggling not only with their own weaknesses, but with religious and political dogmas which spoiled and vitiated even the beginnings of their efforts.  When, in the seventeenth century, men associated themselves in research, for free communication and discussion of their findings, a great invention came alive.  Close on its heels was born the exact experimental method.  Amazing triumphs were born of that marriage which swept away before it ignorance and superstition and prejudice.  Its children and grandchildren have flourished and grown strong and mighty.  They have transmuted the material conditions of life.  Certainly all the laurels belong to the method of absolute, measured observations.