. The Cambridge natural history. Zoology. FLAGELLATA 127 plate bends up (as in the gastrulation of the double cellular plate of the Nematode CucuUanus, Yol. II. p. 136), and finally forms a hollow sphere bounded by a single layer of cells: the site of the original orifice may be traced even in the adult as a blank space larger than exists elsewhere. Among the cells of the young colony some cease to divide, but continue to grow at an early period, and these are destined to become in turn the mothers .^ ofy. Fio. a.— Volvox globator. A, entire colony, enclosing several daiigliter-colouies ; B, t
. The Cambridge natural history. Zoology. FLAGELLATA 127 plate bends up (as in the gastrulation of the double cellular plate of the Nematode CucuUanus, Yol. II. p. 136), and finally forms a hollow sphere bounded by a single layer of cells: the site of the original orifice may be traced even in the adult as a blank space larger than exists elsewhere. Among the cells of the young colony some cease to divide, but continue to grow at an early period, and these are destined to become in turn the mothers .^ ofy. Fio. a.— Volvox globator. A, entire colony, enclosing several daiigliter-colouies ; B, tlie same during sexual maturity ; C, four zooids in optical section ; D'-D", develop- ment of parthenogouidium ; E, ripe spermogonium ; F, sperm ; G, ovum : H, oosperm, a, Partlienogonidia ; fl, fiagellum ; m, ovum ; my, ovaries; pg, pigment spot; sp, sperms ; Spy, spermogonia dividing to form sperms. (From Parker s Biology, after Cohu and Kirctner.) ("parthenogonidia") of a new colony; they begin segmenting before the colony of which they are cells is freed. The young colonies are ultimately liberated by the rupture of the sphere as small-sized spheres, which henceforth only grow by enlargement of the sphere as a whole, and the wider separation of the vege- tative cells. Thus the vegetative cells soon cease to grow ; all the supply of food material due to their living activities goes to the nourishment of the parthenogonidia, or the young colonies, as. 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 Harmer, S. F. (Sidney Frederic), Sir, 1862- ed; Shipley, A. E. (Arthur Everett), Sir, 1861-1927. ed. [London, Macmillan and Co. , Limited; New York, The Macmillan Company
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