The Effect of Temperature on the Spontaneous Activity of Speckled Trout Before and After Various Lesions of the Brain

The frequency of spontaneous movements made by speckled trout was determined at a number of different constant temperatures. The relation between the frequency and temperature was found to be complex, showing two maxima. One of these constantly occurred at approximately the temperature selected by normal trout in a horizontal temperature gradient and the other occurred two to three degrees below the upper lethal temperature.The relation between frequency of movements and temperature was not affected by (1) destruction of the forebrain, (2) by section of the lateral line nerves, or (3) by destruction of both the forebrain and the dorsal part of the cerebellum. Destruction of only the dorsal part of the cerebellum profoundly changed the relation between frequency of movements and temperature: it caused the disappearance of the first peak.Brief consideration was given to the legitimacy of relating the activity of animals in different constant levels of environmental factors with behavior in gradients of these factors.