. The biology of dragonflies (Odonata or Paraneuroptera). Dragon-flies. 214 THE REPEODTJCTIVE SYSTEM [CH. forwards. In the Lihellulidae, the tail is much shorter and less slender. The vas deferens {vd) is a rather narrow tube, which runs along the middle of the inner side of the testis, being enclosed within that organ by the overgrowth'of its lobes around it. It leaves the bent-up end of the testis in the eighth segment, and passes backwards to the ninth. There it makes a small bend or loop, turning forwards, inwards and downwards to enter a short common duct just above the genital pore. In t
. The biology of dragonflies (Odonata or Paraneuroptera). Dragon-flies. 214 THE REPEODTJCTIVE SYSTEM [CH. forwards. In the Lihellulidae, the tail is much shorter and less slender. The vas deferens {vd) is a rather narrow tube, which runs along the middle of the inner side of the testis, being enclosed within that organ by the overgrowth'of its lobes around it. It leaves the bent-up end of the testis in the eighth segment, and passes backwards to the ninth. There it makes a small bend or loop, turning forwards, inwards and downwards to enter a short common duct just above the genital pore. In the mature male, this common duct is dilated dorsally into a conspicuous sperm- sac (sr), lying above the points of entry of the two vasa deferentia. Fig. 94. Mature spermatozoon of Calopteryx splendens Harris ( X 250). h head; m middle- piece ; nu nucleus; t tail. After Biitschli. Fig. 95, Sperm-capsule of Aeschna hrevi- styla Ramb. ( x 330). Original. If the vas deferens of a mature male be opened^, it is found to contain, not separate sperms, but a large number of little round balls, or s'peryn-ca'psides (fig. 95). Each of these is about 0-15 mm. in diameter, and appears to contain the whole mass of sperms derived from a single testis-lobule. The sperms are all radially arranged, their inner ends (apparently the heads) forming a sUght spiral (about a turn and a half) around the centre. Externally, the capsule is enclosed by a thick coat, apparently formed of minute gelatinous globules, one affixed to each sperm. ^ The observation was made with Aeschna 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 Tillyard, Robin John, 1881-1937. Cambridge [Eng. ] : University Press
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