the right side of the heart was then found to contain a higher percentage of sugar than is present in the arteries.  The vein which transmits the blood from the intestines to the liver had the usual lower percentage of sugar corresponding to the analysis established for the other veins.  The liver, therefore, must add sugar to the blood on its way to the heart.  Extraction of the liver then revealed the presence in it of a form of starch, an animal starch, which Bernard called glycogen, the sugar-maker.  The origin of the sugar added to the blood on its way from the liver to the heart was thus settled.  Bernard went on to hail glycogen and the sugar derivable as the internal secretions of the liver, and to erect, and then drive home, a theory of internal secretions and their importance in the body economy.

The case he had hit upon was exquisitely fortunate, as the liver had hitherto been regarded purely a gland of external secretion, the bile.  Nowadays, glycogen and the blood sugar are not considered internal secretions, because they are classified as elementary reserve food, while the concept of the internal secretions has become narrowed down to substances acting as starters or inhibitors of different processes.  Moreover, the process of liberation of sugar from glycogen itself in the liver, upon demand, is today set down to the action of an internal secretion, adrenalin.  Claude Bernard’s conception, like a novelist’s characters, has turned upon its creator, taken on a life of its own, and evolved into something he never intended.  He looked upon an internal secretion as simply maintaining the normal composition of the blood, which bathed alike and treated alike the democracy of cells.  Today, the blood is believed merely the transporting medium for the internal secretion, destined for a particular group of cells.

ADDISON’S AS THE FIRST ENGLISH CONTRIBUTION

The years 1855-56 are red-letter years in the history of the glands of internal secretion.  They witnessed, not only the publication of Claude Bernard’s “Lectures on Experimental Physiology,” but also the appearance of a monograph by Thomas Addison, an English physician, entitled “On the constitutional and local effects of disease of the suprarenal bodies.”  In this, he described a fatal disease during which the individual affected became languid and weak, and developed a dingy or smoky discoloration of the whole surface of the body, a browning or bronzing of the skin, caused generally by destructive tuberculous disease of the suprarenal or adrenal bodies.  Addison promptly put down these constitutional effects of loss of the adrenal bodies to loss of something produced by them of constitutional importance.  He was particularly struck by the change in the pigmentation of the skin, so much so that his own designation for the affection was “bronzed skin.”  Since then, however, the condition has been universally styled Addison’s Disease.