Page:Popular Science Monthly Volume 81.djvu/135

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Before and for some time after these events a great volume of work in physiological chemistry was done in laboratories of organic chemistry and of physiology; but the events at Tübingen and Strassburg served to concentrate attention on physiological chemistry and eventually to hasten the establishment of independent laboratories. For the first few years progress was slow; in 1882, to quote Dr. Marshall again, only two such independent laboratories, those of Tübingen and Strassburg, existed in Germany. In the intervening thirty years the situation has changed. Now, such laboratories exist wherever adequate teaching or intelligent research in medicine is attempted.

The early physiological chemistry was quite different from that with which we are familiar to-day. It was largely the analysis of the chemical composition of various body tissues and fluids. This early conception, however, soon gave way to a dynamic conception, the idea of function, and present-day investigators in physiological chemistry are concerned chiefly with the ways and means of cell action. The chemical constitution of the cell, its enzymes, the methods by which it builds up complex bodies from simple substances, or disintegrates a compound to its simplest constituents; in brief, the problems of digestion, metabolism and secretion in health and disease. These are the problems which concern this science and which, as its methods have been extended to include the study of the vegetable kingdom, as well as the lower forms of animal life, is now more frequently known by the broader term, biological chemistry. The dynamic point of view which to-day characterizes physiological chemistry is largely due to two influences which have come from the outside: (1) The study of intramolecular structure as carried out on the sugars, purins and proteins by the Fischer school, and (2) the study of the nature of chemical reactions, as taught by the modern school of physical chemistry, led by van't Hoff.

Its fundamental problems which during recent years have engaged the attention of its best workers and which still hold their attention are (1) the chemical composition of the protein molecule, (2) the part played by ferments or enzymes in the metabolic changes which occur within the cell and which are responsible for the functions of the various organs and tissues, (3) the general problems of nutrition and the relative values of different food-stuffs, (4) the question of the interrelation of function, that is, of the influence of the secretion of the cells of one organ or tissue on the cells of a remote organ or tissue, (5) the mechanism, from a chemical point of view, of natural and acquired resistance to disease and of phenomena associated with such resistance.

All of these investigations, it is seen, have for their object a better knowledge of the mechanism of cell activity.

Experimental Pharmacology or pharmaco-dynamics, as it is sometimes called, applies the methods of physiology and chemistry to the