. The biology of the cell surface. Cytology. THE BIOLOGY OF THE CELL SURFACE animals breed. Like many other forms, Nereis exhibits a lunar periodicity in its breedins; behavior and is sexually mature only during the period from full to new moon of each lunar cycle from June to September (at Woods Hole, Mass.).^ Although "ripe" eggs of Nereis limbata are available only during this particular moon-phase, their abundance and the clock-like precision of their development make them ideal objects for observation and experiments on fertiliza- tion. The fertilization-pro- cess as seen in the
. The biology of the cell surface. Cytology. THE BIOLOGY OF THE CELL SURFACE animals breed. Like many other forms, Nereis exhibits a lunar periodicity in its breedins; behavior and is sexually mature only during the period from full to new moon of each lunar cycle from June to September (at Woods Hole, Mass.).^ Although "ripe" eggs of Nereis limbata are available only during this particular moon-phase, their abundance and the clock-like precision of their development make them ideal objects for observation and experiments on fertiliza- tion. The fertilization-pro- cess as seen in the living egg is as follows: When discharged or re- moved from the female the egg measures about lOO by 80 microns. It reveals in optical section at the centre a large formation, the germinal Fig. from photo- vesicle. Around this are graphs of Nereis eggs in a suspension of Chinese ink in sea-water (after Lillie). greenish spheres, the yolk, a, before insemination; Z), three minutes among which are larger re- after insemination, c- . IT 1 •! 1 irmgent bodies, the oil drops. Beyond the area of yolk and oil is a rim, the ectoplasm, made up of coarse strands disposed in a somewhat radial fashion which extend to the clearly discerned vitelline mem- brane. The eggs die in this stage with germinal vesicle and ectoplasm intact, unless fertilized or experimentally treated by means of inducing ^Lillie and Just, igi^; Just, /p/^, 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 Just, Ernest Everett, 1883-1941. Philadelphia, P. Blakiston's son & co. , inc
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Keywords: ., bookcentury1900, bookcollectionameri, bookcollectionbiodiversity
