. The Biological bulletin. Biology; Zoology; Marine biology. 446 ANDERSON, LUMER, AND ZUPANCIC pre-adult instars is therefore variable in this species as well as in others (Anderson, 1932). The minimum number of pre-adult instars for Daphnia pulex is probably four. Of the 71 animals primiparous during the fifth instar, 47 lived through the twentieth instar. The data from these 47, summarized in Table I, are the basis for the growth studies which follow. Absolute Growth Figure 3 is a group of growth curves in terms of total length, carapace length, and height. The curves are similar in shape. T
. The Biological bulletin. Biology; Zoology; Marine biology. 446 ANDERSON, LUMER, AND ZUPANCIC pre-adult instars is therefore variable in this species as well as in others (Anderson, 1932). The minimum number of pre-adult instars for Daphnia pulex is probably four. Of the 71 animals primiparous during the fifth instar, 47 lived through the twentieth instar. The data from these 47, summarized in Table I, are the basis for the growth studies which follow. Absolute Growth Figure 3 is a group of growth curves in terms of total length, carapace length, and height. The curves are similar in shape. The. S 10 15 20 Z5 INSTAR Fig. 2. Survival curve for the eighty-two animals observed in these experiments. point of inflection in each curve comes immediately before the instar during which the animals are primiparous. Attempts have been made to fit the Robertson and Gompertz equations to the curves. In neither instance was the result judged satisfactory. The time unit used in this work is the instar. Adult instars have been considered as equivalent physiological time units (Anderson, 1933). At room temperature, each of the first three pre-adult instars lasts approxi- mately one day, the fourth or last pre-adult instar one and a half days, the first adult instar about two days, and each subsequent instar becomes increasingly longer. The use of the instar as a time unit. 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 Lillie, Frank Rattray, 1870-1947; Moore, Carl Richard, 1892-; Redfield, Alfred Clarence, 1890-; Marine Biological Laboratory (Woods Hole, Mass. ); Marine Biological Laboratory (Woods Hole, Mass. ). Annual report; HighWire Press. Lancaster, Pa. [etc. ] : Lancaster Press, inc. [etc. ]
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