. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. Na, K AND Cl IN HYDROIDS 329 K4- exchanges slowly from a medium containing 5 millimolar K and 140 milli- molar Na. An estimated minimum half-time for exchange would he of the order of eight hours. During the three-hour period indicated, influx appears to follow a simple kinetic curve, disregarding a very small initial rapid uptake. The time period was not sufficient to indicate whether or not there was an apparently unexchangeable fraction of K. Na24 exchanges more rapidly (half-time ca. 4 hours for the slow phase) and shows
. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. Na, K AND Cl IN HYDROIDS 329 K4- exchanges slowly from a medium containing 5 millimolar K and 140 milli- molar Na. An estimated minimum half-time for exchange would he of the order of eight hours. During the three-hour period indicated, influx appears to follow a simple kinetic curve, disregarding a very small initial rapid uptake. The time period was not sufficient to indicate whether or not there was an apparently unexchangeable fraction of K. Na24 exchanges more rapidly (half-time ca. 4 hours for the slow phase) and shows a very rapid initial influx. There is some indication that there is a portion, about 25%, of the total Na that is very slowly exchangeable. Influx of Na is at nearly the same rate from 80 millimolar and 140 millimolar external Na concentrations. C. Tubularia Because of the large size and relative delicacy of the hydranths of Tubularia, the results reported will relate only to analyses of stem segments. The data in general. 100 80 O O- -O., __ - - -o. 8 12 16 TIME -HOURS 20 24 FIGURE 4. Influx of Na24 into Tubularia stems. Circles: from choline chloride artificial sea water (MBL formula), Na = 25 mM. Dots : from normal sea water, Na = 440 mM. however, apply to hydranth material, the major differences being those that can be accounted for by the smaller inulin or sulphate space for hydranths (17%) as com- pared to stems (28%). The perisarc of the stems may be regarded as essentially inert with respect to passage of materials. A few experiments in which empty peri- sarc tubes were loaded with K42 sea water showed nearly complete equilibration with an outside medium in five minutes. Insofar as possible with the available material, straight clean stem segments were used. However, some of the colonies, especially later in the season, had extensive branching Please note that these images are extracted from scanned page images that may have been digitally enhanced for reada
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Keywords: ., bookauthorlilliefrankrat, booksubjectbiology, booksubjectzoology
