. The cell; outlines of general anatomy and physiology. Cells; Anatomy; Physiology; Cells; Anatomy; Physiology. 228 THE CELL smaller cell, richer in protoplasm, and a larger one, richer in jolk; in these segmentation proceeds at different rates. Ic. Cell-Budding. "When one of the portions produced by division is so much smaller than the othei", that it appears as though it were only a small appendage to the original cell, scarcely causing any diminution of its substance, the process is called "cell-budding, or gemmative segmentation," the smaller portion being called the bu
. The cell; outlines of general anatomy and physiology. Cells; Anatomy; Physiology; Cells; Anatomy; Physiology. 228 THE CELL smaller cell, richer in protoplasm, and a larger one, richer in jolk; in these segmentation proceeds at different rates. Ic. Cell-Budding. "When one of the portions produced by division is so much smaller than the othei", that it appears as though it were only a small appendage to the original cell, scarcely causing any diminution of its substance, the process is called "cell-budding, or gemmative segmentation," the smaller portion being called the bud, and the larger the mother-cell. Two kinds of cell-budding are distinguished, according to whether one or more buds are formed. In the animal kingdom this process of cell-budding occui^s when the egg is mature, causing the development of the directive cor- puscles, or polar bodies (polar cells). By this term we understand two or three small spherules, w^hich are composed of protoplasm and nuclear substance, and hence are of the same value as small cells; they are frequently situated at the animal pole of the egg, within the vitelline membrane. The course of the process of cell- budding is as follows :— Whilst the germinal vesicle is becoming broken up, a typical I II. IV. V. VI. Pig. 118.—Formation of the polar cells in ^stertas glaciaXis (O. Hertwig, Emhryol., Fig. 13). In Fig. I. the polar spindle (sf) has advanced to the surface of the egg. In Fig. JI. a small protuberance (i-/;i) has been formed, which receives halfof the spindle. In Fig. III. the protuberance Ls constricted off, forming a polar cell (rfci). Out of the remaining halfof the original spindle, a second complete spindle (sp) has developed. In Pig. IV. a second protuberance has bulged out below the first polar cell, which in Pig. V. becomes constricted off to form the second polar cell (rfc^), in Fig. VI. out of the remainder of the spindle the egg nucleus (f/.) Please note that these imag
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