To become adapted to their environment animals are transformers of energy. This adaptation to environment is made by means of a system of organs evolved for the purpose of converting potential energy into heat and motion. The principal organs and tissues of this system are the brain, the adrenals, the thyroid, the muscles, and the liver. Each is a vital link, each plays its particular role, and one cannot compensate for the other. A change in any link of the kinetic chain modifies proportionately the entire kinetic system which is no stronger than its weakest link. In this conception we find a possible explanation of many diseases one which may point the way to new and more effective therapeutic measures than those now at our command. ALKALESCENCE, ACIDITY, ANESTHESIA--A THEORY OF ANESTHESIA[*] [*] Paper delivered before the Virginia Medical Association, Washington, D. C., October 29, 1914. Alkalis and bases compose the greater part of the food of man and animals, the blood in both man and animals under normal conditions being slightly alkaline or rather potentially alkaline; that is, although in circulating blood the concentration of the OH-ions-- upon which the degree of alkalinity depends--is but little more than in distilled water, yet blood has the power of neutralizing a considerable amount of acid (Starling, Wells). At the time of death, whatever its cause, the concentration of H-ions in the blood increases,-- the concentration of H-ions being a measure of acidity,--that is, the potential or actual alkalinity decreases and the blood becomes actually neutral or acid. To determine what conditions tend to diminish the normal alkalinity of the blood, many observations were made for me in my laboratory by Dr. M. L. Menten to determine by electric measurements the H-ion concentration of the blood under certain pathologic and physiologic conditions. As a result of these researches we are able to state that the H-ion concentration of the blood--its acidity--is increased by excessive muscular activity; excessive emotional excitation; surgical shock; in the late stages of infection; by asphyxia; by strychnin convulsions; by inhalation anesthetics; after excision of the pancreas, and in the late stages of life after excision of the liver and excision of the adrenals. Morphin and decapitation cause no change in the H-ion concentration. Ether, nitrous oxid, and alcohol produce an increased acidity of the blood which is proportional to the depth of anesthesia. Many of the cases studied were near death, as would be expected, since it is well known that a certain degree of acidity is incompatible with life. Since alkalis and bases preponderate in ingested food; since alkalinity of the blood is diminished by bodily activity; and since at the point of death the blood is always acid, we may infer that some mechanism or mechanisms of the body were evolved for the purpose of changing bases into acids that thus energy might be liberated.