[Postnatal weight gain in albino mice under various light regimens]

The following experiments on male and female mice of the strain AB Jena Halle were designed to study the effect of various light regimens on the body weight during the postnatal development from birth to 60 days of age. Characteristic phases of the increase in weight appear in both cyclic illumination (12L:12D, 50 lux) and constant light (24 L, 50 lux). These phases are dependent upon the wavelength and the effective period of light. Such a phase is pronounced in the puberal period in which was found a relationship between the body weight and the wavelength. At the end of the experiments, remarkable low body weights appear in red exposition in both sexes, specially in the females. Continuous white or coloured light effects, in principle, a more distinctive sec-dimorphism of the body weight than 12L:12D, because the increase of the body weight of the males is higher in 24L: as in 12L: 12D. Female mice did not show such a reaction. It follows from the results that various light regimens and various light qualities influence the postnatal increase of body weight.