. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. CLEAVAGE FURROW IN ARBACIA EGGS 283 these treatments may increase the elastic strength of the egg surface by toughening the extra cortical structures, but it is probable that they favor cortical gelation as well. Hypotheses concerning the mechanism of cleavage; surface tension Chambers and Kopac (1937) found that clean oil drops of the proper inter- facial tension with sea water, will coalesce spontaneously with a naked egg (Arbacia, Lytechinus, and Echinometra). They state: "The tendency to coalescence in the furrow an
. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. CLEAVAGE FURROW IN ARBACIA EGGS 283 these treatments may increase the elastic strength of the egg surface by toughening the extra cortical structures, but it is probable that they favor cortical gelation as well. Hypotheses concerning the mechanism of cleavage; surface tension Chambers and Kopac (1937) found that clean oil drops of the proper inter- facial tension with sea water, will coalesce spontaneously with a naked egg (Arbacia, Lytechinus, and Echinometra). They state: "The tendency to coalescence in the furrow and polar zones of cleaving eggs (late amphiaster and later) was investi- gated and no difference was ; They used oils whose approximate tensions in contact with sea water were 30, 10, and 3 dynes per cm. The fact that coalescence occurs at all indicates a fluid layer around the egg periphery. Spontaneous coales-. FlGURE 47 cence does not occur in Amoeba protcus (Kopac and Chambers, 1937), which in- dicates a non-fluid surface. In view of these observations any surface tension hypothesis is untenable. Subcortical currents Chambers (1938) has hypothesized that cleavage results from the activity of "the sub-cortical currents (which) sweep around the two asters and add gelating material to the inwardly growing ; In this hypothesis he combines his own observations with those of Schechtman (1937) on localized cortical growth during the cleavage of the amphibian egg. It was shown in the present paper (page 280) that normal furrowing may be associated with abnormal currents, which argues against the importance of such currents for division; moreover Lewis (1942) found no currents in the dividing 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 Marine Biological Laboratory (Wood
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Keywords: ., bookauthorlilliefrankrat, booksubjectbiology, booksubjectzoology
