. Outlines of zoology. Zoology. 96 PROTOZOA. In V. globator the two kinds of reproductive cells are usually formed in the same colony, the spermatozoa generally first. Technically, the colony is usually a protandrous hermaphrodite. In V. aureus the colony is oftenest unisexual or dicecious, , either male or female. But it may be monoecious or hermaphrodite, and then generally protog}'nous, , producing eggs first. Whether in a hermaphrodite or in a unisexual colony, the sex cells appear among the ordinary vegetative units ; the ova are distinguishable. Fig. 24.—Volvox globator. (After C
. Outlines of zoology. Zoology. 96 PROTOZOA. In V. globator the two kinds of reproductive cells are usually formed in the same colony, the spermatozoa generally first. Technically, the colony is usually a protandrous hermaphrodite. In V. aureus the colony is oftenest unisexual or dicecious, , either male or female. But it may be monoecious or hermaphrodite, and then generally protog}'nous, , producing eggs first. Whether in a hermaphrodite or in a unisexual colony, the sex cells appear among the ordinary vegetative units ; the ova are distinguishable. Fig. 24.—Volvox globator. (After Coiix.) a. Balls of sperms ; b. immature ova ; c. ripe o\-a. by their larger size, the "sperm mother cells " divide rapidly and form numerous (32-100 or more) slender spermatozoa, each with two cilia. In V. globator their bundles may breal< up within the parent colony; or, as always in V. aureus, they may escape intact, and swim about in the water. In any case, the ovum is fertilised by a spermatozoon, and, after a period of encystation and rest, segments to form a new colony. Occasionally, however, this organism, so remarkable a condensation of reproductive possibilities, exhibits a parthenogenetic development of ova. Here then we have an organism, on the border line between plant. 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 Thomson, J. Arthur (John Arthur), 1861-1933; Newbigin, Marion I. (Marion Isabel), 1869-1934; Smith, Preserved, 1880-1941. fmo. New York, D. Appleton & Co.
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Keywords: ., bookcentury1800, bookdecade1890, booksubjectzoology, bookyear1895
