Outlines of zoology . vox is found, not very commonly, in fresh-water pools,and is usually classed by botanists as a green Alga. Itconsists of numerous biflagellate individuals, connected byfine protoplasmic bridges, and embedded in a gelatinousmatrix, from which their flagella project, the whole forminga hollow, spherical, actively motile colony. In V. globatorthe average number of individuals is about 10,000; inV. aureus or minor, 500-1000. The individual cells arestellate or amoeboid in V. globator, more spherical in ; each contains a nucleus and a contractile vacuole. VOL vox. 99 A
Outlines of zoology . vox is found, not very commonly, in fresh-water pools,and is usually classed by botanists as a green Alga. Itconsists of numerous biflagellate individuals, connected byfine protoplasmic bridges, and embedded in a gelatinousmatrix, from which their flagella project, the whole forminga hollow, spherical, actively motile colony. In V. globatorthe average number of individuals is about 10,000; inV. aureus or minor, 500-1000. The individual cells arestellate or amoeboid in V. globator, more spherical in ; each contains a nucleus and a contractile vacuole. VOL vox. 99 At the anterior hyaline end, where the flagella are inserted,there is a pigment spot; the rest of the cell is green, owingto the presence of chlorophyll corpuscles. In consequenceof the presence of these, Volvox is holophytic, it feedsas a plant does and builds up starch granules. In its method of reproduction Volvox is of much biological interestand importance. As Klein, one of its best describers, says, it is an. Fig. 43.—Volvox globator.—After , Balls of sperms ; h, immature ova ; c, ripe ova. epitome ot the evolution of sex. Some of the colonies are these a limited number of cells possess the power of dividing up to-form little clusters of cells; these clusters escape from the envelope ofthe parent colony, and form new free-swimming colonies. In othercolonies there are special reproductive cells, which may be called ovaand spermatozoa. In V. globator the two kinds of reproductive cells are usually formedin the same colony, the formation of spermatozoa generally precedingthat of the ova. Technically the colony may then be described as aiprotandrous hermaphrodite. 100 PHYLUM PROTOZOA—THE SIMPLEST ANIMALS. In V, aureus the colony is oftenest unisexual or dioecious, eithermale or female. But it may be monoecious or hermaphrodite, and isthen generally protogynous, producing eggs first. Whether in a hermaphrodite or in a unisexual colony, the
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Keywords: ., bookcentury1900, bookdecade1910, bookidcu3192, booksubjectzoology
