. Fresh-water biology. Freshwater biology. 796* FRESH-WATER BIOLOGY skeleton of whorled radiating spines. The efferent duct leads to a tube, the vas deferens, which in turn leads to the penis (Fig. 1246 a). These forms may also be propagated from unfertilized eggs, , by parthenogenesis. In such cases there may be a sexual genera- tion followed by a number of such parthenogenetic generations. Again, In some forms males have never been discovered, even after as many as 18 years of continuous observation by very care- d. Fig. 1246. Cyprinotus dentata (a) Penis, X 210; (6) Efferent or
. Fresh-water biology. Freshwater biology. 796* FRESH-WATER BIOLOGY skeleton of whorled radiating spines. The efferent duct leads to a tube, the vas deferens, which in turn leads to the penis (Fig. 1246 a). These forms may also be propagated from unfertilized eggs, , by parthenogenesis. In such cases there may be a sexual genera- tion followed by a number of such parthenogenetic generations. Again, In some forms males have never been discovered, even after as many as 18 years of continuous observation by very care- d. Fig. 1246. Cyprinotus dentata (a) Penis, X 210; (6) Efferent or ejaculatory apparatus; (c) Cross- section of same, X 293: (i) Part of a spermatozoon, X 525; (e) Right maxillary palp of male, X 158; if) Left palp of same; ig) Extremity of testicular tube, showing spermatocysts, X 120; (A) Ma- ture spermatocysts, X 120. ful observers. Herpetocypris reptans is a good example. Thus some authors distinguish four types of the method of propagation, as follows: 1. Always sexual as in Notodromas monacha, Cyclocypris laevis, Cypria ophthalmica. 2. Temporarily parthenogenetic, as in Candona Candida, Cypri- dopsis vidua. 3. Locally parthenogenetic, as in Cypris incongruens. 4. Always parthenogenetic, as in Herpetocypris 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 Ward, Henry Baldwin, 1865-1945; Whipple, George Chandler, 1866-1924. joint author. New York, John Wiley & sons, inc. ; [etc. ,etc. ]
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Keywords: ., bookcentury1900, bookdecade1910, booksubjectfreshwa, bookyear1918
