. Biological effects of radiation; mechanism and measurement of radiation, applications in biology, photochemical reactions, effects of radiant energy on organisms and organic products. Radiation; Biology. 1324 BIOLOGICAL EFFECTS OF RADIATION necessary for a division of the nuclei is according to Huettner (49) 10 min. at 23°C. Packard (75) places the time at 1 hr. at 13°C. and 15 min. at 28°C. The numbers of nuclei in the eggs would increase in geometrical ratio with time. If the cause of death in irradiation is the production of dominant lethal mutations, the susceptibility of the egg should
. Biological effects of radiation; mechanism and measurement of radiation, applications in biology, photochemical reactions, effects of radiant energy on organisms and organic products. Radiation; Biology. 1324 BIOLOGICAL EFFECTS OF RADIATION necessary for a division of the nuclei is according to Huettner (49) 10 min. at 23°C. Packard (75) places the time at 1 hr. at 13°C. and 15 min. at 28°C. The numbers of nuclei in the eggs would increase in geometrical ratio with time. If the cause of death in irradiation is the production of dominant lethal mutations, the susceptibility of the egg should change from the time it is in the single-nucleus stage, when theoretically it should be twice as susceptible as the sperm, to double the susceptibility at each. 8 920 17 840 26 760 REOUCEO SCALE- 35 680 X-RAYS (eSu/SEC/CM^; AMOUNT OF IRRADIATION FiQ. 4.—Survival curves for Drosophila eggs (at 1 to 3 hr. from laying), chromatin diploid, and sperm, chromatin haploid. rhythm of cell division provided each nucleus is essential to further devel- opment. According to Packard's work, the Drosophila eggs do increase in sensitivity until they are most sensitive at 2 hr. from laying, when they become less sensitive. This becoming less sensitive seems also to have a meaning in the course of development. Patterson (79, 80) and Gowen (23) showed that the anlage of the adult eye of Drosophila was in the one-celled stage not longer than 12 hr. after the egg was laid and very possibly less time than that. If the vital organs differentiate even more rapidly so that they become two-celled early in development, requiring that both be destroyed to cause the egg's death, then a multiple- absorption curve will be necessary to account for the observed deaths. This increase gives the appearance of increased resistance of the cell to X-rays after such a critical period is passed. The data are not accurate. Please note that these images are extracted from scanned page images that may have been digi
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