PRIZE ESSAY. WHAT PHYSIOLOGICAL VALUE HAS PHOSPHORUS AS AN ORGANISMAL ELEMENT? AN ESSAY TO WHICH WAS AWARDED THE PRIZE OF THE AMERICAN BY SAMUEL R. PERCY, M. D., PROFESSOR OF MATERIA MEDICA IN THE NEW YORK MEDICAL COLLEGE, PROFESSOR OF PHYSICIAN TO MT. SINAI HOSPITAL, ETC. ETC. RECIPIENT OF THE PRIZE OF THE AMERICAN MEDICAL ASSOCIATION FOR THE YEAR 1863, AND ALSO FOR PREFACE. SOME six years ago, while sailing from Bridgeport to New York, a strange gentleman, who was seated near me, lent me a pamphlet written by Professor Wilson. Making that my text, and carrying out the current of thoughts and ideas suggested by it, with the deeper research and experiments I felt compelled to undertake, I have written the present essay. It has often been suggested by medical men and others, that physiological chemistry in all its relations should be made as interesting a subject to the student, or general reader, as history. In these pages I have tried to meet this desire. The text will be found as free as possible from the purely technical, while in the appended notes the chemistry proper and its nomenclature are entered for those who desire to refer to them. INTRODUCTION. THE investigations of chemists have taught that living organisms are not accidental congregations of atoms, or different kinds of elements thrown promiscuously together in indefinite quantities. Chemistry has taught that each animal or plant, each separate organism, is definite and permanent in its chemical composition; but that individual parts differ, each organ having its own composition, which differs sometimes slightly, sometimes very materially from other organs in close proximity to it; thus, a bone differs very materially in its chemical composition from the periosteum surrounding it, and bone and periosteum both differ from the muscle attached to them. Each distinct genus of animals, or plants, has passed through the unnumbered centuries since creation with the same structural development, and the same chemical formula of embodiment. Within very narrow bounds, this is constant with each species; and individuals of the same species are chemically, as well as anatomically, alike. There are certain chemical elements that are necessary to an organ, they are invariably present in it, and they are also invariably present in the same organ of every individual of the species. Of the numerous elements that are offered to it, every organism has the power of selecting the chemical elements that are needed for its composition and structural development; also in an equal degree the power of rejecting such elements as are not needed, or are in too large quantities for its use. Plants, for example, readily absorb and appropriate all the potassa or soda they can find in the soil in which they grow; but they reject the alumina. Animals readily absorb and appropriate all the phosphate of lime they find in the vegetable food they eat; but, with a very trifling exception, they reject the silica that the plants offer in large quantities. Elements that are presented in the greatest abundance are not necessarily absorbed in proportion to their abundance, but are |