Elementary text-book of zoology (1884) Elementary text-book of zoology elementarytextbo0101clau Year: 1884 summer generation which is found in autumn and spring and lives through the winter: the males are, in most cases, not yet known. The closely-allied Aphides (plant- lice), which were formerly supposed to present the phenomenon of an alterna- tion of generations, behave in a similar manner. In them the summer genera- tions are very numerous, and are suc- ceeded by a sexually-developed autumn ' . . Fie;. 452.—Micropyles (Mk) of insect generation, which includes winged males eggs (after R
Elementary text-book of zoology (1884) Elementary text-book of zoology elementarytextbo0101clau Year: 1884 summer generation which is found in autumn and spring and lives through the winter: the males are, in most cases, not yet known. The closely-allied Aphides (plant- lice), which were formerly supposed to present the phenomenon of an alterna- tion of generations, behave in a similar manner. In them the summer genera- tions are very numerous, and are suc- ceeded by a sexually-developed autumn ' . . Fie;. 452.—Micropyles (Mk) of insect generation, which includes winged males eggs (after R* Leuekart). «, , well as the oviparous and often ap- terous females (tig. 97. ). In the spring, viviparous Aphides are developed from the fertilized eggs. These are mostly winged (tig. 99), and in their organisation closely resemble true females. Their reproduc- tive organs are, however, differently constructed, and are without the receptaculum seminis. Since they never copulate, they have often been regarded as asexual forms provided with germ tubes. upper part of the egg-shell of Aiifliomyiti; b, egg of Droxojiliili r, Ihirix • c, egg of tegtaceug.
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