The cell in development and inheritance . double germinal spot,consisting of a chromatic and an achromatic sphere. This egg is heavily laden with yolk, in theform of clear deiitoplasm-spheres {d^ and fat-drops (/), uniformly distributed through the cyto-plasm. The peripheral layer of cytoplasm (peri-vitelline layer) is free from deutoplasm. Outsidethis the membrane. B. The egg some time after fertilization and about to divide. The deuto-plasm is now concentrated in the lower hemisphere, and the peri-vitelline layer has are the two polar bodies (/.*.). Below them lies the
The cell in development and inheritance . double germinal spot,consisting of a chromatic and an achromatic sphere. This egg is heavily laden with yolk, in theform of clear deiitoplasm-spheres {d^ and fat-drops (/), uniformly distributed through the cyto-plasm. The peripheral layer of cytoplasm (peri-vitelline layer) is free from deutoplasm. Outsidethis the membrane. B. The egg some time after fertilization and about to divide. The deuto-plasm is now concentrated in the lower hemisphere, and the peri-vitelline layer has are the two polar bodies (/.*.). Below them lies the mitotic figure, the chromosomesdividing. I30 THE GERM-CELLS serving as storehouses of material formed incidentally to the generalnuclear activity, but not of further direct use. Carnoy and Le Brun (97, 99) reach, however, the conclusion thatin the germinal vesicle of Amphibia the chromosomes are derivednot from the chromatin-network, but solely from the nucleoli. Theapparent contradiction of this result with that of other observers is,. Fig. 61. — Germinal vesicles of growing ovarian eggs of the lamellibranch, Uiiio (A-£>), andthe spider, Epeira {E-F). [Obst.] A. Youngest stage with single (principal) nucleolus. B. Older egg, showing accessory nucle-olus attached to the principal. C. The two nucleoli separated. D. Much older stage, showingthe two nucleoli united. E. Germinal vesicle of Epeira, showing one accessory nucleolus at-tached to the principal, and one free. F. Later stage; several accessory nucleoli attached to theprincipal. perhaps, only a verbal one; for the nucleoli are here evidentlychromatin-masses, and the disappearance of the chromatic network iscomparable with what occurs at a later period in the annelid egg(Figs. 97, 128). 2. The Cytoplasm The egg-cytoplasm varies greatly in appearance with the varia-tions of the deutoplasm. In such eggs as those of the echinoderm THE OVUM 131 (Fig. 58), which have little or no deutoplasm, the cytoplasm forms aregular m
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Keywords: ., bookcentury1900, bookdecade1900, booksubjectcells, bookyear1902
