. The biology of dragonflies (Odonata or Paraneuroptera). Dragon-flies. XI] THE REPRODUCTIVE SYSTEM 221 Posteriorly, the egg-strings open into the oviduct (ovd), a thin- walled cyhndrical tube, down which the eggs pass one by one. Fertihzation is supposed to take place here. The two oviducts open posteriorly in the eighth segment into a large pouch, the spermatheca or bursa (6). The walls of this pouch are very thick and muscular, and are further strengthened by an internally projecting ring or collar of hard chitin. Its cavity is often found to be distended with masses of spermatozoa. Opening
. The biology of dragonflies (Odonata or Paraneuroptera). Dragon-flies. XI] THE REPRODUCTIVE SYSTEM 221 Posteriorly, the egg-strings open into the oviduct (ovd), a thin- walled cyhndrical tube, down which the eggs pass one by one. Fertihzation is supposed to take place here. The two oviducts open posteriorly in the eighth segment into a large pouch, the spermatheca or bursa (6). The walls of this pouch are very thick and muscular, and are further strengthened by an internally projecting ring or collar of hard chitin. Its cavity is often found to be distended with masses of spermatozoa. Opening dorsally into the bursa, by the union of their two short ducts, is a pair of elongated ovoid sacs, the accessory sacs {as). In mature females these sacs are tightly swollen and smooth, their rounded ends directed forwards and lying at the level of the eighth gangUon {ng^). At other times they are wrinkled and collapsed. In some forms they appear as coiled tubes or caeca. The genital pore opens between the eighth and ninth segments, mid-ventrally. 2. External Organs (figs. 99-104). The external genitaha of the female Dragonfly consist typically of three pairs of ventral processes or gonapophyses, outgrowths of the integu- ment in the region of the genital pore. They begin to develop early in larval Ufe, but have nothing to do with the primitive paired segmental appendages of the abdomen, which, as already stated above, are lost during embryonic life. The three pairs together form the ovipositor, or organ for use in the process of egg- laying. Van der Weele [192] has made an excellent study of the development and structure of this organ. As it is greatly reduced in a large number of Odonata {Gomjphinae, Lihellulidae), it is necessary to select a form having a well-developed ovipositor, if we would understand its structure correctly. For this purpose we have chosen Synlestes weyersi (fig. 99).. Fig. 99. Ovipositor of Syn- lestes weyersi Selys, $ ( X 10). ap anterior pro- cesses;
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