. The Biological bulletin. Biology; Zoology; Marine biology. 122 A. BACHEM AND M. A. DUSHKIN towards 240 m/x, where the spectrum becomes too weak for exact in- vestigations. Our results disagree with all those authors who maintain that the bactericidal powers of the ultraviolet increase with the decreas- ing wave length, but they agree with the findings of Gates, and Ehris- mann and Noethling in that the bactericidal power decreases after a peak between 254-280 m/x, to a level about 240 m^. Our findings also sustain those of Gates, and Ehrismann and Noethling in that we have not found certain
. The Biological bulletin. Biology; Zoology; Marine biology. 122 A. BACHEM AND M. A. DUSHKIN towards 240 m/x, where the spectrum becomes too weak for exact in- vestigations. Our results disagree with all those authors who maintain that the bactericidal powers of the ultraviolet increase with the decreas- ing wave length, but they agree with the findings of Gates, and Ehris- mann and Noethling in that the bactericidal power decreases after a peak between 254-280 m/x, to a level about 240 m^. Our findings also sustain those of Gates, and Ehrismann and Noethling in that we have not found certain wave lengths to be specific for certain organisms, but we have found that with minor variations, the spectral distribution of the bactericidal action seemed to be the same for the various organisms. Problem of Ultraviolet " Stimulation " Exposures of agar plates inoculated with bacteria to ultraviolet light were observed by several authors to show an increased growth of the bacterial colonies at the border of the exposed areas. This they at- tributed to stimulation caused by the scattered ultraviolet light of weak intensity. We use the term " stimulation " merely because it was uti-. Fig. 11. Marginal growth on agar plate sprayed with B. prodigiosus; squares protected against spray; circle exposed to ultraviolet light. lized by these observers, although the phenomenon does not conform to the physiological definition of stimulation. Browning and Russ ob- served increased growth between two adjacent areas of destruction and. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Lillie, Frank Rattray, 1870-1947; Moore, Carl Richard, 1892-; Redfield, Alfred Clarence, 1890-; Marine Biological Laboratory (Woods Hole, Mass. ); Marine Biological Laboratory (Woods Hole, Mass. ). Annual report; HighWire
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