. The Biological bulletin. Biology; Zoology; Marine biology. 206 ARLENE JOHNSON DELAMATER good proportions but the ex-conjugants never survived. In two to three days, after conjugation in the culture, the ex-conjugants became small, either subsequently disappearing or forming what appeared to be cysts. Attempts at ex-cystment were unsuccessful. Similar results for the ex-conjugants from 128 conjugating pairs which were isolated in fresh DoO medium were obtained. These also could not be revived in per cent D2O and disappeared after a time. Twenty-four conjugating animals were placed in nor
. The Biological bulletin. Biology; Zoology; Marine biology. 206 ARLENE JOHNSON DELAMATER good proportions but the ex-conjugants never survived. In two to three days, after conjugation in the culture, the ex-conjugants became small, either subsequently disappearing or forming what appeared to be cysts. Attempts at ex-cystment were unsuccessful. Similar results for the ex-conjugants from 128 conjugating pairs which were isolated in fresh DoO medium were obtained. These also could not be revived in per cent D2O and disappeared after a time. Twenty-four conjugating animals were placed in normal medium; 3 within ten days, but the other 21 survived, rates, however, were not tested. The normal control animals will be designated as Group A; deriva- tives from them, as Group B, as shown in Fig. 2. The former group of the ex-conjugants died Their subsequent fission. Fig. 3. Effects of per cent on fission rate and length of life cycle of animals immersed in it at various ages. Group A ( ), in spring water; Group C ( ), D (——), and E (•••). in per cent DoO. Group C introduced into D2O when mature, Groups D and E introduced into D2O when old. Abscissa = ten-day periods. Ordinate = mean number of fissions in ten days. survived for 31 ten-day periods and its fission rate was practically the same as that of Group B. This similarity existed both in Periods 11 to 13, when Group B was carried in special control water; and during the following six periods, when Group B was carried in normal medium. This shows that any changes found in the per cent D^O medium are not due to the presence of injurious agents, since this special control water was carried through the same process as the 95 per cent D2O from which the 50 per cent DgO was diluted. At the end of Period 2, when the animals were in the forty-fifth to forty-eighth generations, derivatives (Group C) from each of the con- trol lines were placed in per cent D2O, and allowed to remain until the
Size: 2419px × 1033px
Photo credit: © Library Book Collection / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1800, bookdecade1890, booksubjectb, booksubjectzoology
