. Elementary text-book of zoology. Zoology. PARTHENOGENESIS—HETEROGAMY. 543 ovum a single (Forficula), or a number of yolk-forming cells (nutri- tive cells), so that we can distinguish in the egg-tube alternate yolk and germ compartments (rig. 453, a and b). In rare cases (Aphides} there is at the end of each egg-tube a common larger chamber of yolk cells, which are connected with the egg-chambers by means of " yolk- cords " (tig. 453 c). Parthenogenesis and Heterogamy.—In certain insects, partheno- genesis, , spontaneous development of unfertilized ova, has been shown to obtain
. Elementary text-book of zoology. Zoology. PARTHENOGENESIS—HETEROGAMY. 543 ovum a single (Forficula), or a number of yolk-forming cells (nutri- tive cells), so that we can distinguish in the egg-tube alternate yolk and germ compartments (rig. 453, a and b). In rare cases (Aphides} there is at the end of each egg-tube a common larger chamber of yolk cells, which are connected with the egg-chambers by means of " yolk- cords " (tig. 453 c). Parthenogenesis and Heterogamy.—In certain insects, partheno- genesis, , spontaneous development of unfertilized ova, has been shown to obtain ; this occurs in the Psychidce (Psyche), TineiJo- (Solenobia), Coccidce (Lecanium, Aspidiotus) and Chermes; also in numerous Hymenop- tera, especially in Bees, Wasps, Cynipidce, and Tenthredinidce (Nematus). In the Hymenoptera which live together in the so-called animal communities, male forms only are produced from the unfer- tilized ova, (arrentokia). Chermes affords an example of Heterogamy, in that two different oviparous generations follow one another; a slender and winged generation, and an apterous. summer. 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 Claus, Carl, 1835-1899; Sedgwick, Adam, 1854-1913; Sinclair, F. G. (Frederick Granville), b. 1858. New York : Macmillan
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Keywords: ., bookcentury1800, bookdecade1880, booksubjectzoology, bookyear1884
