. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. REGULATION OF CHLORIDE IN GOLDFISH 301 Great care was taken not to disturb the fish unduly during the weighings, be- cause handling itself can induce loss of weight and of chloride. The fish, which apparently got accustomed to the weighing procedure, were carefully transferred from their chambers into nets which were drained on filter paper. From the nets the fish were put into weighing-glasses without being touched directly by the hands. Weighings were made in duplicate. The fish were returned to water between the two weigh
. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. REGULATION OF CHLORIDE IN GOLDFISH 301 Great care was taken not to disturb the fish unduly during the weighings, be- cause handling itself can induce loss of weight and of chloride. The fish, which apparently got accustomed to the weighing procedure, were carefully transferred from their chambers into nets which were drained on filter paper. From the nets the fish were put into weighing-glasses without being touched directly by the hands. Weighings were made in duplicate. The fish were returned to water between the two weighings which were thus performed under the same conditions. The weight in grams was read with two decimals and rounded to 0 or 5. The duplicates deviated maximally by 100 mg. Daily changes in weight should therefore amount to g. or more in order to be significant. Total exchangeable chloride was determined in three well-nourished goldfish which were kept in 200 ml. tap water enriched with Cl36-labelled sodium chloride. Changes in specific activity of the chloride in the medium were followed. From the - O 5/0/5 2O 25 FIGURE 1. Spontaneous changes in chloride content of 5 starving goldfish, initially weighing 11-19 g. degree of dilution of Cl36 the amount of chloride in medium plus goldfish was com- puted. Radioactivity was measured on evaporated samples of the medium by means of a Geiger-Muller end-window counter. RESULTS Variations in chloride content were followed during several weeks in five gold- fish. As may be seen from Figure 1, uptake or loss of chloride often continued for several days or even weeks at a time, resulting in large changes in total chloride content of the body. One fish, weighing 19 g., took up 600 //.eq. of chloride in 27 days, and another one, weighing 17 g., took up 575 jueq. in 22 days. Total ex- changeable chloride, determined in three fed goldfish, was found to be , and body weight. Assuming an initial chloride c
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Keywords: ., bookauthorlilliefrankrat, booksubjectbiology, booksubjectzoology
