Lethal and Quasi-Lethal Effects Produce by Monochromatic Ultra-Violet Irradiation

Abstract

Lethal and quasi-lethal effects produced by monochromatic ultra-violet irradiation of biological material representing the phyla Bacteria, Fungi, Angiospermae, Protozoa and Arthropoda have been observed and recorded over a range of wavelengths from 254 to 365 mµ. Although the materials represent high and low forms in both vegetable and animal kingdoms, there is a striking similarity in their behaviour. There is a sudden increase in the lethal effect between 313 and 297 mµ, in every case. Although the curves connecting lethal dose with wave-length are closely similar in all cases, the absolute magnitudes of doses are widely different. The ratio of lethal doses for different material may be as high as two hundred to one at corresponding wave-lengths. The ratio of the greatest to the least dose recorded is of the order of a million to one. Tables and curves are given recording lethal and quasi-lethal doses for the different materials at different wave-lengths, and brief accounts of the conditions in which the experiments were conducted are given in the text. An interesting correlation is exhibited between the form of the lethal dose curves and the ultra-violet radiation in daylight.