. Comparative animal physiology. Physiology, Comparative; Physiology, Comparative. 42 Comparative Animal Physiology is not significantly different once they are adapted in media of different tonici- ties. Figure 18 gives the rate of fluid elimination as a function of external concentration. In actively feeding specimens "the rate of elimination is in- versely linearly proportional to the concentration of the culture ;^^'"' Vahlkampfia calkensi, an amoeba parasitic in the oyster digestive tract, was kept growing and multiplying in sea water on agar. ^^"^ Under these co
. Comparative animal physiology. Physiology, Comparative; Physiology, Comparative. 42 Comparative Animal Physiology is not significantly different once they are adapted in media of different tonici- ties. Figure 18 gives the rate of fluid elimination as a function of external concentration. In actively feeding specimens "the rate of elimination is in- versely linearly proportional to the concentration of the culture ;^^'"' Vahlkampfia calkensi, an amoeba parasitic in the oyster digestive tract, was kept growing and multiplying in sea water on agar. ^^"^ Under these condi- tions it had no contractile vacuole. When it was transferred to a similar agar culture made up with tap water or distilled water, one'or more vacuoles devel- oped and pulsated regularly. The more active the amoebae were, the more frequent the pulsations. Several species of marine Peritricha survive in dilute sea water. In a dilute medium the volume rises slightly; the vacuolar output initially rises, then decreases to a new steady value higher than that occurring in 100 per cent sea water (Fig. 19). It was possible to balance exactly the increased vacuolar output by adding a nonelectrolyte of proper concentration. Kalmus ^-^ made TIME IN MINUTES i?0 . IQO 240 ^ I llOOXSW 12 l^X SW. 120 ISO TIME IN MINUTES Fig. 19. Body volume in cubic micra (upper half of figure) and excretory output from contractile vacuole (lower half of figure) in marine peritrich Cothtirnia successively in normal sea water, in I2V2 per cent sea water, in 121/2 per cent sea water containing m/500 cyanide, in llVi per cent sea water, in I2V2 per cent sea water containing m/500 cyanide, in 121/2 per cent sea water, and in normal sea water. From Kitching.^^^ similar observations on the marine ciliate Amphileptus gutta. After a week in 70 per cent sea water the vacuolar rate was 21 per cent higher than in normal sea water; in 60 per cent sea water and lower concentrations, hypervacuohza- tion was noticed. N
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