THE SPECIFIC EFFECTS OF MONOCHROMATIC LIGHT ON THE GROWTH OF PARAMOECIUM

Abstract
Paramoecium was irradiated with monochromatic light and it was found that rays of different frequencies have specific effects upon its growth. Certain frequencies in the red, the yellow and the near ultra-violet parts of the spectrum were found to stimulate growth; some as in the green and in the far ultraviolet beyond 3000Å retarded it, and even killed the organism at a very low intensity. Other frequencies retarded or stimulated growth during early exposure and later produced the reverse effects.