V. Experiments on the action of light on Bacillus anthracis

It is abundantly evinced by experiments that direct insolation in some way leads to the destruction of spores ofBacillus anthracis , and in so far the results merely confirm what had already been discovered by Downes and Blunt in 1877 and 1878. From the fact that an apparent retardation of the development of the colonies on plates exposed to light was observed several times under circumstances which suggested a direct inhibitory action of even ordinary day-light, the author went further into this particular question with results as startling as they are important, for if the explanation given of the phenomena observed in the following experiments turns out to be the correct one, we stand face to face with the fact that by far the most potent factor in the purification of the air and rivers of bacteria is the sun-light.