. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. 340 MASAO SUGIYAMA fertilized before the anaphase, the polysperniic division takes place at the time of the first cleavage. However, if the eggs are re-fertilized after the full growth of the amphiaster, the process of the first cleavage goes on normally and polyspermic irregularity becomes visible at the second cleavage. It is of especial interest to note that the eggs are re-fertilizable even at the 2-cell stage if they have been al- lowed to develop in sea water after the treatment mentioned above. As shown in Figure 2, t
. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. 340 MASAO SUGIYAMA fertilized before the anaphase, the polysperniic division takes place at the time of the first cleavage. However, if the eggs are re-fertilized after the full growth of the amphiaster, the process of the first cleavage goes on normally and polyspermic irregularity becomes visible at the second cleavage. It is of especial interest to note that the eggs are re-fertilizable even at the 2-cell stage if they have been al- lowed to develop in sea water after the treatment mentioned above. As shown in Figure 2, the eggs re-fertilized at the 2-cell stage become abnormal later on. Isotonic solutions also of glycerine or thiourea are found to be effective for mak- ing the fertilized eggs re-fertilizable, while sea water containing ether, Cu-ion, trypsin, lipase, NaOH or HCl is not. Ca-Mg-free sea water becomes ineffective when any of Ca++, Mg++, Sr++ or Ba++ is added. It may be concluded that those media which contain any divalent cation are 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 (Woods Hole, Mass. ); Marine Biological Laboratory (Woods Hole, Mass. ). Annual report 1907/08-1952; Lillie, Frank Rattray, 1870-1947; Moore, Carl Richard, 1892-; Redfield, Alfred Clarence, 1890-1983. Woods Hole, Mass. : Marine Biological Laboratory
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