. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. DEVELOPMENT IN POECIIJI1) FISHES 235 proximate diameter measured with an ocular micrometer. The weight determina- tions were made as described for Heterandria (Scrimshaw, 1(M4), the embryos being dried on small cover slips over calcium chloride and weighed on a Sartorius balance. Any error in the actual dry weight recorded was insignificant in com- parison with the variability of the material. Wet weights are not discussed be- cause of their variability in preserved material and the difficulties in determining excess fluid.
. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. DEVELOPMENT IN POECIIJI1) FISHES 235 proximate diameter measured with an ocular micrometer. The weight determina- tions were made as described for Heterandria (Scrimshaw, 1(M4), the embryos being dried on small cover slips over calcium chloride and weighed on a Sartorius balance. Any error in the actual dry weight recorded was insignificant in com- parison with the variability of the material. Wet weights are not discussed be- cause of their variability in preserved material and the difficulties in determining excess fluid. The taxonomic scheme followed throughout is that proposed by Hubbs (1924, 1926). EXPERIMENTAL Dry weight determinations of the eggs and embryos in the intact ovisac were made at various stages between fertilization and parturition. In each case as many stages as could be obtained were studied and ranked according to age as described below for purposes of graphical and statistical representation. It was soon observed that these weights were within the same general range re- gardless of the stage of the embryo. When least square lines were calculated through these points, a straight line parallel to the abscissa served to describe the data. Figures 1 and 2 show representative development lines and the scatter of weight values for four of these species. 5 < o: 2o 10 o: o POECILIOPSIS © © 30 © © 0 0 © P. OCCIDENTALS O to 2 < o: o 3 O P. IN FANS a: p ALLOGAMBUSIAond DARIENICHTHES. O o o o o A. Tfll DENT IGE R 468 RELATIVE TIME UNITS 10 468 RE L ATIVE TIME UNITS 10 FIGURE 1. The dry weights of the embryos in the intact ovisac are arranged on a relative time axis in order of stage of development. For graphical and statistical purposes it has been necessary to assume that the time between stages is equal in all cases. Fertilization is repre- sented at the beginning of the time scale and parturition at the end. The lines are calculate! through these points by the meth
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Keywords: ., bookauthorlilliefrankrat, booksubjectbiology, booksubjectzoology
