The efficient and economical liberation of this energy in the body is dependent not only upon the completeness of digestion. the readiness of absorption and assimilation. and the efficiency of the circulation. but much depends also upon the proper working of the excretory apparatus. Waste products formed in oxidation must he removed. otherwise the physiological rhythm is interfered with. The ashes and clinkers must be taken front the human furnace if the fires are to he kept burning freely. For this purpose, the skin, lungs. and kidneys are efficient channels, and the study of the excretions poured through these several emunctorWs throws much light upon the extent and character of the oxida tion going on in the body. It is a truism that the chemical study of the urine throws light especially upon the extent and character of the proteid metabolism going on in the body. The nitrogenous waste 10'0(100 s—those come from the breaking down of proteid material— find their outlet through the urine, and abnor malities ill this excretion have a significance easy of interpretation.
It 11111:it not be overlooked, in considering the domain of physiological chemistry. that its scope is a broad one. The chemical processes going on in the animal body, for example, are multi tudinous. There are few functions in which physiological chemistry does not play some part, and the light which its study throws upon physi ology as a whole can hardly be estimated. The phenomenon of museular contraction is in great part chemical. Until the discovery of muscle plasma and the contained myosinogen by Kiihne, physiologists were in the clerk regarding what took place inside the musele-fihre during con traction and after the death of the fibre. The discovery of glycogen in the liver by Claude Bernard, and the relationship of glycogen to the sugar of the blood. opened up the whole subject of the glycogenic function of the liver, and thereby paved the way for a (dearer understand ing of the function of carbohydrate material in the body. The subject of and the mode of formation of the digestive enzymes from their precursors, the z•mogens. inside the cells of the glands. was unraveled in great part through the appliention of chemical methods by Hull eminent physiologists as Corvisart.
Ileidenhain. and Langley.
The study of lymph-formation was rendered possible through the use of chemical methods. and the same methods of study have t;in,!dit physiologists all that is known regarding the chemical nature of the blood. its various ical constituents, and the various harts played by the serum, plasma. and corpuscles in the co
agulation of the blood and in many normal and ahno•nmI processes.
Metabolism in the liver—aside from glyeogen formation—has had much light thrown upon it by chemical methods of study, and the whole laliad subject of internal secretion and the duct less glands has been helped forward at a rapid pace by the \Toil; of physiological chemists, who have unraveled in part the chemical nature of the specific substances responsible for the physio logical action of the various secretions.
Lastly, mention may he made of the Fla \\ hiell physiological chemistry is now playing in the development of our knowledge concerning bacteriology and the infectious diseases. The micro-organisms which arc responsible for the various infections diseases now preying on man kind owe their action in great part to specific chemical poisons which they produce. The elle111 lea I 11;11.11re and physiological action of these poisons is being carefully studied, and, with fuller knowledge of their properties, ready meth ods for combating these diseases will be avail able. Even to-day our knowledge of these toxins is considerable, and more than one antitoxin has been discovered by which immunity can he seemed or a logical method of treatment devised. Here is a large and practical fiehl for the appli cation of the principles and methods of physio logical chemistry, and we may hope in the near future for such an extension of our of bacterial poisons as will enable us to cope successfully With these destroyers of health and life. A study if physiological chemistry prom ises. expansion of knowledge eoncerning, the nor mal ehanges occurring in the organism. and also affords a means of recognizing the approach of abnormal conditions, the forerunners of disease and death.
BIBLIOGRAPHY. 'Waller and Symes, ElemenBibliography. 'Waller and Symes, Elemen- tary Physiological Chemistry (London, 1897) ; Mingo, Test-Book of Physiological a ml Pat Ito logic,' I Chem ist ry. trans. by Woolbridge ( London, 1890; new Cerman ed. Leipzig, 1891) llammar sten, A Test-Book of Physiological Chemistry, trans. by (New York, 1893) ; Wurtz, Trail(' de chi in ie biologique (Paris, 1880-85) ; Sal kowski, der ph ysiologischen and hologischen Chemie (Berlin, I893) ; lloppe Seyler. Handbuch der physiologisch- and pat ho logisch-chcmischen .1 nal yse f Ur der:de and St ml irendc (Berlin, 1893) ; Neumeister, Lela- bitch der physiologis•hot Chemie (Jena, 1597 ) The substances forming the chemical basis of the organisms of animals and plants may be found descrilicd under their special names. See also Foot).