. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. 426 RICHARD A. ORMSBEE growth was hours for this set of experiments. Population counts were obtained by using as the diluent conditioned 2 per cent proteose peptone in which ciliates had been grown for the same length of time as those in the experimental flask. The organisms were killed by gentle heating in a flame, centrifuged out, and the supernatant used as the dilu- ent. Following dilution of a sample of the experimental culture the dilu- tions were allowed to stand for ten minutes following which the counts were ma
. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. 426 RICHARD A. ORMSBEE growth was hours for this set of experiments. Population counts were obtained by using as the diluent conditioned 2 per cent proteose peptone in which ciliates had been grown for the same length of time as those in the experimental flask. The organisms were killed by gentle heating in a flame, centrifuged out, and the supernatant used as the dilu- ent. Following dilution of a sample of the experimental culture the dilu- tions were allowed to stand for ten minutes following which the counts were made. When a fresh 2 per cent proteose peptone was used as the o < QL O L_ O o o. B o CONDITIONED DILUENT • FRESH DILUENT ® FISSIONS 10 20 30 40 HOURS 50 60 80 FIG. 1. Population and fission curves in 2 per cent proteose peptone. The dotted line represents the theoretical fission curve. All curves are on the same ordinate. diluent, curve B was the result. This curve indicates the presence of an increased sensitivity of the organisms as the population approaches the end of the phase of exponential growth. This sensitivity was not ap- parent in the early exponential phase and gradually disappeared in the hours following the end of the exponential phase. It was later found that accurate counts (5 per cent) could be made using fresh proteose peptone as the diluent if the diluting and counting procedure were completed within five minutes. The average fission time will of course vary with the criteria of the investigator. In this study fission was arbitrarily assumed to have begun when the first external indication of the cytokinesis could be observed using a dissecting binocular microscope with 10 X oculars and. 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 Marine Biological Laboratory (Woods Hole, Mass
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Keywords: ., bookauthorlilliefrankrat, booksubjectbiology, booksubjectzoology
