. The Biological bulletin. Biology; Zoology; Marine biology. 114 A. BACHEM AND M. A. DUSHKIN for a few hours. Stenstrom and Gaida (1931) claim that bacterial re- sistance to ultraviolet light grows with increasing incubationary periods prior to exposure. This we find to be true only after the period of maximum sensitivity has been passed. Figure 6 shows another inter- esting experiment in which the exposures on the left were made one-half hour after plating, and those on the right were made 6 hours after plat- ing. The total energies applied over each exposed area were identical, 100. O 2 4- 6
. The Biological bulletin. Biology; Zoology; Marine biology. 114 A. BACHEM AND M. A. DUSHKIN for a few hours. Stenstrom and Gaida (1931) claim that bacterial re- sistance to ultraviolet light grows with increasing incubationary periods prior to exposure. This we find to be true only after the period of maximum sensitivity has been passed. Figure 6 shows another inter- esting experiment in which the exposures on the left were made one-half hour after plating, and those on the right were made 6 hours after plat- ing. The total energies applied over each exposed area were identical, 100. O 2 4- 6 8 IO Hours growth Fig. 5. Sensitivity of B. prodigiosus depending upon incubation temperature and time. but three values of exposure times and intensity applications were used. The order of the exposures were such that those opposite to each other on the plate were identical. Thus the equal bacterial destruction on one side of the plate upholds the Bunsen-Roscoe law. However, the finding of increased bactericidal action after 6 hours supports our as- sumption that sensitivities change with different incubationary periods, and that the Bunsen-Roscoe law will hold only for those periods in which there is no change in the bacterial sensitivity. To study further the time-sensitivity effect, we endeavored to make our observations during the period of maximal sensitivity and minimal variation of sensitivity. We exposed bacterial plates to ultraviolet light while we used different exposure times and varied the intensity by means. 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, P
Size: 1673px × 1494px
Photo credit: © Library Book Collection / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1800, bookdecade1890, booksubjectb, booksubjectzoology
