. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. 366 W. M. MORAX AXD R. E. TULLIS with an Oxford Titrator by the mercuric titration method of Schales and Schales (1941). Measurement oj wet-weight changes as an indicator oj volume regulation Chitons were placed in the maintenance SW on preweighed plastic petri dishes and allowed 2-3 days to attach to them. The petri dish plus the chiton was weighed and then placed into 2 1 of aerated experimental SW and weighed at 1, 2, 4, 6, 8, 12, and 24 hr. Wet weights were determined by removing the petri dish with the attached chiton f
. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. 366 W. M. MORAX AXD R. E. TULLIS with an Oxford Titrator by the mercuric titration method of Schales and Schales (1941). Measurement oj wet-weight changes as an indicator oj volume regulation Chitons were placed in the maintenance SW on preweighed plastic petri dishes and allowed 2-3 days to attach to them. The petri dish plus the chiton was weighed and then placed into 2 1 of aerated experimental SW and weighed at 1, 2, 4, 6, 8, 12, and 24 hr. Wet weights were determined by removing the petri dish with the attached chiton from the S\V, blotting dry. and immediately weighing on an analytical balance to the nearest g. Nine replicate weighings of a single chiton in 100% SW gave a standard deviation of ± body wet weight. The small volume of water trapped in the mantle cavity of the chitons was assumed to remain unchanged during the experiment. The resulting small overestimates of the chiton's true wet weight were too small to seriously affect conclusions about volume regulation. Lange and Mostad (1967) have criticized volume-regulation experiments using whole animals: They state that weight variations could be caused by excretion and loss of fecal pellets. Few fecal pellets were seen in the containers during volume- regulation experiments with M. nntscosa; defecation probably did not contribute to the variability in wet-weight determinations. However, excretion remains a possible source of variation. The effect of temperature on volume regulation was studied by holding the chitons for 2-3 hr in 100% SW at either 7° or 19°C and then placing them in 60% SW of the same temperature and monitoring wet weights at 0, 2, 4, 6, 8, 12, and 24 hr. Calculations of osmotic permeability (I',,*) and oj chitons as osmoiiictcrs Calculations of osmotic permeability, Pos, and the theoretical rate of weight change of chitons responding as if they were perfect osmometers were based on the wet weight of the so
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Keywords: ., bookauthorlilliefrankrat, booksubjectbiology, booksubjectzoology
