. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. 548 LEVON A. TERZIAN AND NATHAN STAHLER that it was almost impossible to isolate any effect of radiation. No hatch whatso- ever could be obtained from 270-day-old control eggs. It is evident from the data presented in Figure 1 that resistance or susceptibility to radiation was related to the age of the egg. During the first 24-hour period fol- lowing oviposition, a time of active embryonic development, the eggs were particu- larly susceptible to radiation damage, so that as little as 800 r caused a 50 per cent reduction in h
. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. 548 LEVON A. TERZIAN AND NATHAN STAHLER that it was almost impossible to isolate any effect of radiation. No hatch whatso- ever could be obtained from 270-day-old control eggs. It is evident from the data presented in Figure 1 that resistance or susceptibility to radiation was related to the age of the egg. During the first 24-hour period fol- lowing oviposition, a time of active embryonic development, the eggs were particu- larly susceptible to radiation damage, so that as little as 800 r caused a 50 per cent reduction in hatch while 6000 r inhibited hatching entirely. By the time the eggs were 48 hours old and embryonic development was nearly complete, however, their resistance had increased so markedly that it required 7500 r to produce a 50 per cent reduction in hatch and r to eliminate hatching entirely. During the period in which hatching would have normally occurred (third day), resistance was still further increased so that it required 30,000 r to effect a 50 per cent reduc- tion in hatch. Resistance to radiation increased to maximal dosage levels in four- and five-day-old eggs so that it required 75,000 r to produce a 50 per cent reduc- tion in hatch, and at least 130,000 r to inhibit hatching completely. Further aging gradually lessened resistance, however, until by the 180th day after oviposition, administration of 4000 r reduced the hatch by 50 per cent although it still required some 75,000 r to eliminate hatching completely. Progeny were reared from eggs of various ages irradiated at dosages ranging from 1000 r to 2500 r and there was no discernible evidence to indicate that the age of the egg influenced in any way ro O 130- X 120- z o 110- Q C£ 100- 4 90- 80- 1 70- 0 60- O 50- LJ «. CD O Q 30- 10 -I. o = 50% HATCH • = NO HATCH. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appear
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Keywords: ., bookauthorlilliefrankrat, booksubjectbiology, booksubjectzoology
