for we find him exclaiming, when the opportunity loomed of a great laboratory on Agassiz Island, Long Island, on one of his recurrent flights to New York:  “Would that I were thirty!” And other passages in his personal communications refer again and again to his consciousness of growing old.  The miracles that were being performed by injecting thyroid and feeding thyroid in animals probably acted as the spark to an inflammable mass of ideas long smouldering in the subcellars of his mind.  The effects were reported to the Society of Biology in Paris, one memorable evening, June 1, 1889, in two notes on the results of the hypodermic injection in man of the testis juice of monkeys and dogs, and certain generalizations deduced therefrom.  Such juices, he stated, had a definite energy-mobilizing or, as he put it, dynamogenic action upon the subject himself, stimulating amazingly his general health, muscular power and mental activity.

These experiments, their nature, the manner in which they were conducted, the character and age of the experimenter, and the results claimed, were exquisitely good stuff for ridicule.  Cartoonists and reporters leaped upon the theme with the avidity of the true-blue interviewer.  Paris, where to be ridiculed is to be killed in public with the most ignominious of deaths, reacted as only the French temperament can react.  The wits of the salons crackled, the bourgeoisie chortled, the proletariat roared.  The Elixir of Life had been discovered and it was excellent sport.

But Brown-Sequard remained unshaken.  He had all the roues of Paris running to him, and consequent charges of quackery and charlatanism.  How much of these unsavory epithets really applied to him will not be determined until we have a better acquaintance with his more intimate life.  A biography and collection of his letters is needed.  But it is certain that the general principles he arrived at, aided as much by the wings of intuition as by the clues of incomplete and incompletely controlled experiments, survive as the foundations of whatever we know about the internal secretions, and all our present viewpoints.  He summed these up in 1891 as follows: 

“All the tissues, in our view, are modifiers of the blood by means of an internal secretion taken from them by the venous blood.  From this we are forced to the conclusion that, if subcutaneous injections of the liquids drawn from these parts are ineffectual, then we should inject some of the venous blood supplying these parts....  We admit that each tissue, and, more generally, each cell of the organism, secretes on its own account, certain products or special ferments, which, through this medium (the blood), influence all other cells of the body, a definite solidarity being thus established among all the cells through a mechanism other than the nervous system....  All the tissues (glands and other organs) have thus a special internal secretion, and so give to the blood something more than the waste products of metabolism.  The internal secretions, whether by direct favorable influence, or whether through the obstacles they oppose to deleterious processes, seem to be of great utility in maintaining the organism in its normal state.”