THE EFFECT OF TEMPERATURE ON THE MECHANICAL ACTIVITY OF THE GILLS OF THE OYSTER (OSTREA VIRGINICA Gm.).

1. The method is described whereby the rate of flow produced by the gills of the oyster can be measured accurately. 2. The rate of doing work in maintaining a constant current along the glass tube can be expressed by the formula W = 2pilmicro S(2), where W = ergs/sec., l = length of the tube, micro = viscosity in poises, and S = speed at the axis of the tube. 3. The relationship between the rate of doing work and the temperature cannot be described by the equation of Arrhenius. 4. The optimum temperature for the mechanical activity of the gills lies between 25 degrees and 30 degrees C. Below 5 degrees no current is produced, though the cilia are beating. Ciliary motion stops entirely at the freezing temperature of sea water. 5. The factors responsible for the production of current are discussed. The study of the relations between the variability of the rate of flow and the temperature shows that between 15 degrees and 25 degrees C. the absolute variability remains constant and increases considerably above 25 degrees and below 15 degrees . The rôle of the coordination in the production of current is discussed, and the conclusion is reached that coordination is affected by the changes in temperature.