when we have attained a clear view of its biological basis.
The progress of chemico-physiological research during recent years has now brought us to new ground for our building. Indeed the image might well be changed altogether, and it might be said that science has entirely transferred the drama of reproduction to a new stage with new actors. Therewith the immense emphasis placed on excretion, and the inevitable reaction that emphasis aroused, both alike disappear. The sexual protagonists are no longer at the surface but within the most secret recesses of the organism, and they appear to science under the name of Hormones or Internal Secretions, always at work within and never themselves condescending to appear at all. Those products of the sexual glands which in both sexes are cast out of the body, and at an immature stage of knowledge appeared to be excretions, are of primary reproductive importance, but, as regards the sexual constitution of the individual, they are of far less importance than the internal secretions of these very same glands. It is, however, by no means only the specifically sexual glands which thus exert a sexual influence within the organism. Other glands in the brain, the throat, and the abdomen,—such as the thyroid and the adrenals,—are also elaborating fermentative secretions to throw into the system. Their mutual
