THE VAPOR TENSION RELATIONS OF FROGS

Abstract

Frogs exposed to atmospheres of constant temperatures, humidities, and air motions were weighed at frequent intervals. All exchanges of water vapor, and of heat as computed from these, were referred to the surface area of the body. At constant temperature and air motion the rates of evaporation were nearly inversely proportional to the relative humidities. Pithing, stopping the circulation, and removing the skin did not change the rates of evaporation significantly. In saturated atmospheres evaporation still goes on, due to the production of heat by metabolism; hence no equilibrium of vapor tension can be established for the living organism. In unsaturated atmospheres heat is lost by evaporation to lower the body temperature to a point where the body gains an equal amount of heat from the environment. These gains are by calculation roughly apportioned among conduction, convection, and radiation.