. Comparative animal physiology. Physiology, Comparative; Physiology, Comparative. 16 Comparative Animal Physiology adjusted to 20 per cent sea water was put back into 100 per cent sea water there was water loss and salt intake so that the worm soon had only 80 per cent of the weight it initially had in 100 per cent sea water. By repeated transfer from 100 per cent to 20 per cent sea water and back, the weight in 100 per cent sea water could be reduced to half. This indicates that water is transferred more rapidly than salt. The ratio of chloride output to water intake in 20 per cent sea water
. Comparative animal physiology. Physiology, Comparative; Physiology, Comparative. 16 Comparative Animal Physiology adjusted to 20 per cent sea water was put back into 100 per cent sea water there was water loss and salt intake so that the worm soon had only 80 per cent of the weight it initially had in 100 per cent sea water. By repeated transfer from 100 per cent to 20 per cent sea water and back, the weight in 100 per cent sea water could be reduced to half. This indicates that water is transferred more rapidly than salt. The ratio of chloride output to water intake in 20 per cent sea water is nearly double the ratio of the exchanges in 100 per cent sea water, hence swelling is much less than in N. cultrifera, where the. Fig. 6. Freezing point of body fluids, Ai^Oi Nereis diversicolor, •, Arenicola marina, and +, N. pelagica; animals adapted to dilutions of sea water indicated by freezing points, Ao. Data from ;" chloride loss is very slow. Whether the avenue of chloride loss is through the nephridia or not is unknown. Several mechanisms favor osmoregulation in N. diversicolor. The permea- bility of the skin is important in volume regulation. Calcium decreases the skin permeability to water and thus prevents a continued rise in volume. Body wall contraction opposes swelling. After an initial increase the volume de- creases as chloride is lost and hypertonicity is maintained; this must, as Krogh points out, necessitate the elimination of hypotonic fluid, possibly by way of nephridia, and is an active process requiring energy. There may, in addition, be active salt absorption from the dilute medium. The mechanism of osmo-. 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 Prosser, C. Ladd (Clifford Ladd), 1907-; Bishop, David W. Philadelphia, Saunders
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