. 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. REGENERATION 431 the ionization chamber of Failla, in use at the Marine Biological Labora- tory in the summer of 1930. Immediately after irradiation the worms were divided by transverse cutting into pieces approximately 2 mm. in length and checked against controls obtained in the same manner which regenerated normally. In each series the irradiates healed their cut surfaces. In the series ex
. 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. REGENERATION 431 the ionization chamber of Failla, in use at the Marine Biological Labora- tory in the summer of 1930. Immediately after irradiation the worms were divided by transverse cutting into pieces approximately 2 mm. in length and checked against controls obtained in the same manner which regenerated normally. In each series the irradiates healed their cut surfaces. In the series exposed to 4000 and to 6000 r there was a slight development of the brain and eyes when the pieces were killed 41 days ??=SS*^S3P5J552^:^. Fig. 11.—Effect of X-rays upon posterior regeneration of Tuhifex tuhifex as shown by microphotographs of whole mounts. 1, X-rayed worm 7 days after removal of posterior segments; 2, control 7 days after a similar removal; .3, control and X-rayed specimens 14 days after such removal; 4, control and X-rayed 21 days after removal; 5, control and X-rayed 30 days after removal. Plane of removal shown by line in each figure. {From Stone, 58.) after exposure. In the 8000 r and in the 12,000 r series there was healing and the pieces were normal in appearance, but there was no evidence of regeneration externally when they were killed at 41 days. A preliminary histological examination showed no beginnings of regener- ating organs and an absence of embryonic cells, although other cells appeared normal as seen in the sections. Since the irradiated pieces were in good condition when killed, there was as good reason to believe that death would have resulted eventually from starvation as that it would have resulted from any delayed effects of the irradiation. Com- pletion of this study by Coldwater has been delayed. In view of the general resemblances between the histological factors of regeneration in nemerteans and planarians and the fact that nemertean
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