Page:Popular Science Monthly Volume 86.djvu/100

96 extract by Murray and Howitz in 1893. In 1884, Sir Victor Horsley produced an experimental myxœdema by removal of the thyroid in monkeys, which were found to survive much longer than dogs. It was also found by Allara (1885), Ewald (1890) and others, that experimental thyroidectomy is negative in birds, rodents and herbivorous animals, and that, both in animals and man, operative myxœdema is produced less frequently as age advances. In 1888, Sir Felix Semon, in an important collective investigation, showed that cretinism, myxœdema and operative myxœdema (eachexia thyreopriva) are one and the same. In 1889, Brown-Séquard, then aged seventy-two, found himself vastly rejuvenated as to general health, muscular power and mental activity, by the subcutaneous injection of testicular extracts, the active principle of which Poehl, the Russian physiologist, holds to be the substance spermin (C5H14N2). These experiments of Brown-Séquard easily lent themselves to ridicule, but he followed them up, even to the extent of giving pituitary extract for disease of that organ (1893), and it was his work upon these extracts which led him to formulate the following statement of the old Bordeu theory of internal secretions:

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 tissues 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, 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 or 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 hindrances of deleterious processes, seem to be of great utility in maintaining the organism in its normal state.

As theory goes, nothing new has been added to the doctrine of internal secretions since Brown-Séquard stated it in this form in 1891. In his essay on "Variation" (1868) Darwin seems to have had a glimmering of the idea when he stated that gemmules are transported from all parts of the body to the ovum to insure their reproduction (pangenesis), and the Bayliss-Starling doctrine of the "hormones" or chemical messengers, as we shall see, is not essentially different from that of Bordeu and Brown-Séquard.

From the time of Brown-Séquard on, experimental investigation of the subject moved so rapidly and in so many different directions that the general trend of the theory became obscured or lost in the details of controversy. And further obfuscation was brought about by the constant succession of dissolving views of the subject of carbohydrate