Acceleration of Rate of the Early Chick Embryo Heart by Visible Light

Abstract

IN the course of an investigation of the control of the heart rate in the early chick embryo it was noted that under certain conditions exposure to visible light accelerates the rate. The following report presents a study of this phenomenon. There are many reports in the older literature of effects of visible light, unrelated to ultraviolet radiation, on cellular activity. Cessation of amoeboid activity when Pelomyxa was suddenly exposed to light was noted in 1879¹, and has been extensively studied more recently^2,3. Activity of cells in tissue culture is affected by exposure to light; amoeboid activity of lymphocytes in frog spleen explants⁴, and the rate of beat⁵ of explants of 6 day chick embryo hearts and of cilia of explants of frog throat epithelium, are all modified by growth of the cultures in visible light. Recently, there have been reports of increased metabolic activity⁶ and of accelerated growth rate and early hatching^7,8 in chick embryos from eggs incubated in permanent light. The stimulation of the chick embryo heart rate to be reported here was obtained in the visible range without addition of dye or photosensitizing agents.