. The Biological bulletin. Biology; Zoology; Marine biology. 110 A. BACHEM AND M. A. DUSHKIN meter, the energy being given as ergs. The reciprocal value of this figure represents the " average sensitivity " of the bacteria in terms of the area in square millimeters over which 1 erg must be distributed in order to destroy 50 per cent of the bacteria. Intensity and Time It is therefore important for us to know whether the bacterial sensi- tivity depends on the time during which the ultraviolet light was applied. According to Schwartzschild, identical biological effects should be ex-. O
. The Biological bulletin. Biology; Zoology; Marine biology. 110 A. BACHEM AND M. A. DUSHKIN meter, the energy being given as ergs. The reciprocal value of this figure represents the " average sensitivity " of the bacteria in terms of the area in square millimeters over which 1 erg must be distributed in order to destroy 50 per cent of the bacteria. Intensity and Time It is therefore important for us to know whether the bacterial sensi- tivity depends on the time during which the ultraviolet light was applied. According to Schwartzschild, identical biological effects should be ex-. O Fig. 1. 6 10 12 Seconds exposure 14 16 18 20 Lethal effects of ultraviolet on B. prodigiosus plotted on linear scale. Intensity (cold quartz lamp) ergs/(). pected if is constant; i representing the intensity of the rays, t the exposure time, and n an exponent usually smaller than 1. Bunsen and Roscoe, however, maintain that a constant product of should pro- duce identical effects (the Schwartzschild exponent being 1 in this for- mula). According to the Bunsen and Roscoe law, the same energy should be required to destroy 50 per cent of the bacteria no matter whether the intensity be decreased or increased, and the exposure time prolonged or shortened correspondingly. This, when expressed in our terms, means that the average sensitivity is unaffected by intensity 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 Press. Lancaster, Pa. [etc. ] : Lancaster Press, inc. [etc. ]
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