. Journal of experimental zoology. inety-five parts sea-waterplus five parts 2^ M KCl at a. m. Part a was transferredto sea-water at p. m. (fifty-five minutes). The designationofthis experiment is thus At p. m. many eggs had reachedthe elongated condition shown in Figs. 57 and 58 with two terminalmasses of yellow^ endoplasm, and a broad equatorial band of ecto-plasm through which the large nucleus could clearly be seen. At Elementary Phenomena of Embryonic Development 233 5 P. M. the ectoplasmic band in many eggs had ruptured on oneside transforming it into a saddle-sha
. Journal of experimental zoology. inety-five parts sea-waterplus five parts 2^ M KCl at a. m. Part a was transferredto sea-water at p. m. (fifty-five minutes). The designationofthis experiment is thus At p. m. many eggs had reachedthe elongated condition shown in Figs. 57 and 58 with two terminalmasses of yellow^ endoplasm, and a broad equatorial band of ecto-plasm through which the large nucleus could clearly be seen. At Elementary Phenomena of Embryonic Development 233 5 P. M. the ectoplasmic band in many eggs had ruptured on oneside transforming it into a saddle-shaped mass, and the two massesof endoplasm met and fused on the opposite side of the egg (). The nuclear area is situated beneath the ectoplasmicaccumulation. It is undoubtedly at this time that the chromatic matter of thenucleus intermingles with the ectoplasm, though I did not observethis in 1904 for the simple reason that the eggs were not examinedunder pressure. But in 1905 this phenomenon was observed asalready Fig. 65 Fig. 64 Fig. 66 Figs. 64 to 70. Later differentiation of uninucleated unsegmented eggs from life. Fig. 64. Form produced by rupture of ectoplasmic band on one side. Eggs put in ninety-fiveparts of sea-water plus five parts 2A M KCl at a. m. Transferred to sea-water at ^- ^-jdrawn at 5 p. m., five hours from beginning of experiment. Fig. 65. Slightly later stage than 64. Fig. 66. Same egg as sixty-five drawn three minutes later; the ectoplasm has overflowed a largepart of the endoplasm. All stages of the rupture of the ectoplasmic band were observed;the notes read all stages may be seen; the granular band (ecto-plasm) first becomes broader on one side, then the yolk masses(endoplasm) approach and fuse and the band ruptures. Thusthe yolk has the characteristic shape shown in the figure. Then the ectoplasm accumulates in a mass (Fig. 65) and 234 Frank R. Lillie immediately begins to spread rapidly over the surface of the egg(Figs. 66
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