OBSERVATIONS ON THE DIURNAL TEMPERATURE VARIATION OF CYNOMOLGUS MONKEYS (Macaca irus) AND ON THE EFFECT OF CHANGES IN THE ROUTINE LIGHTING UPON THIS VARIATION

Abstract

Cynomolgus monkeys which were kept one per cage in an animal room which the sun-light could freely enter, exhibited a distinct diurnal rhythm of body temperature taken from the rectum. The maximum temperature (mean =38.84[degree]C) was recorded at 4 p. m. and the minimum (mean = 37.42[degree]C) was at 4 a. m. The range of d. t. v. (diurnal temperature variation) was 1.42[degree]C. The pattern of d.t.v. of cynomolgous monkey, that was kept one per cage in the room which was artificially illuminated by fluorescent lamps during 10 a. m. -5 p. m. each day preceeded and followed by an entire darkness, was not essentially different from the pattern which was observed under the sun-light condition (the control pattern). The inversion of the pattern of d. t. v. was induced one to 2 weeks after the inversion of routine lighting. In this case, lights were on during 5 p. m. -10 a. m.. The maximum temperature was obtained at 10 a. m. and the minimum was at 4 p. m. in the inverted pattern. When monkeys were continuously left in an entire darkness or in artificial light, the d. t. v. seemed to lose the normal control pattern, and the range of d. t. v. evidently decreased. With changing the experimental conditions of lighting again to the same one as that of the control, the altered patterns of d. t. v. returned to the same pattern as the control in every experimental group. Although the pattern of d. t. v. of cynomolgus monkeys was undoubtedly dependent upon the given condition of lighting, the after-effect of pre-existing condition remained for some time.