Grundriß einer Meteorobiologie des Menschen

Seasonal variations in serum inorganic phosphate and calcium with special reference to parathyroid activity

“…With respect to the physiological significance of the seasonal variations in serum phosphate concentration, little is known except that growth of bone also undergoes seasonal changes in childhood (de Rudder, 1952). Seasonal changes in blood phosphate might also be expected to affect carbohydrate metabolism and energy production.…”

“…Since the level of inorganic phosphate in the blood of infants could be raised by frequent exposure to ultra-violet light (Hess & Gutman, 1921), it was concluded that the increase in the blood-phosphate level in summer and the decrease in winter were related to seasonal variations in the intensity of ultra-violet light. More recently de Rudder (1952) has suggested that this seasonal variation in the blood-phosphate level in infants is intimately connected with corresponding variations in rate of growth.…”

Annual Rhythm of Human Reproduction: II. Environmental Correlations

“…Most of these social annual rhythms are not based directly on biological reactions to environmental changes and are certainly not controlled by an endogenous biological clock. However, human biology is also rhythmic on an annual basis: Physiological (De Rudder, 1952;Lacoste and Wirz-Justice, 1989), endocrinological (Reinberg and Lagoguey, 1978), and immunological (Shifrine, 1982) variables show systematic variations over the year. These annual rhythms of human biology must be under an environmental control, and they may even be driven by an endogenous clock synchronized with the seasons.…”