On the Critical Thermal Increment for the Locomotion of a Diplopod

A good deal of attention has been paid to the temperature coefficients of vital processes. The data available up to 1914-15 are for the most part collected in Kanitz' (1915) book. The chief interest of this work has centered about the "R. G. T." (van't Hoff) rule. In common with many chemical reactions, at ordinary temperatures the velocities of a variety of protoplasmic activities are found to be about doubled or trebled by a 10 ° rise of temperature. The temperature coefficient, Q,0, giving the ratio of velocities for an interval of 10 °, is a quite imperfect means of characterizing a process. I t is in any case not a constant quantity, but depends upon the particular temperature. Moreover, it is known that in the neighborhood of certain temperatures, varying with the process considered, abrupt changes occur in the temperature relations of many biological phenomena. A means is required of dealing with these "critical points." Such complexity of dynamical balance as must be postulated for living matter leads one to expect that by considerable change of temperature a different fundamental reaction might be brought into control of the velocity of a given phenomena. For certain vital activities which may be taken as typical,, it is found that the underlying or controlling processes may be treated as systems of "irreversible" first order reactions (Osterhout, 1914, 1922; Hecht, 1918-19, 1918-19, a; Osterhout and Haas, 1918-19).