. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. 488 KATSUMA AND JEAN CLARK DAN granules of this color appear, as nearly as can be determined, immedi- ately below the protoplasmic surface film (Plate I, Z?-l). Unfertilized Eggs in Section.—Unfertilized eggs treated with OsO4 show a layer of blackened granules, which are distinguished from other granular inclusions by their slightly larger size, and lie so closely beneath the protoplasmic surface (Plate I, C-l) that they appear to be in contact with it. Fertilized Eggs in White Light.—In less than two minutes after fer- til
. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. 488 KATSUMA AND JEAN CLARK DAN granules of this color appear, as nearly as can be determined, immedi- ately below the protoplasmic surface film (Plate I, Z?-l). Unfertilized Eggs in Section.—Unfertilized eggs treated with OsO4 show a layer of blackened granules, which are distinguished from other granular inclusions by their slightly larger size, and lie so closely beneath the protoplasmic surface (Plate I, C-l) that they appear to be in contact with it. Fertilized Eggs in White Light.—In less than two minutes after fer- tilization or after artificial activation, the egg in optical section presents a quite different picture, aside from the appearance of the fertilization membrane and the gradually thickening hyaline plasma layer. In white light, beneath the protoplasmic surface film, a zone of extremely finely. fertilization membrane hyaline plasma layer protoplasmic surface film extra-granular zone row of large colored granules endoplasm FIG. 1. Diagram of fertilized egg of Stronyyloccntrotns pulcherrimus in sea water. granular (but not hyaline) protoplasm has appeared, apparently as a result of the centripetal migration, by approximately /*, of the coarse granules which had been occupying this region (Fig. 1 and Plate I, A-2, A-3). This zone, which will hereafter be called the "extra-granular zone," gradually widens, reaching a width of about 2 p. before cleavage begins. Centripetal to the extra-granular zone and forming an outer boundary to the central heterogeneous granular protoplasm is a slightly irregular ring of larger, definitely orange granules, whose color is trans- mitted to the adjacent extra-granular zone. If the focus is raised, it can be seen that the upper surface no longer gives off the orange radiation which appeared in the unfertilized egg. Fertilized Eggs in Filtered Light.—When observed with filtered light, the fertilized egg in optical section is seen to
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Keywords: ., bookauthorlilliefrankrat, booksubjectbiology, booksubjectzoology
