Fig. 84.—Section through a young female Gordius tolosanus. (From von Linstow.) a, Cuticle; b, hypodermis; c, muscular layer; d, parenchyma; e, alimentary canal; f, nervous system; g, egg-sac; h, ovary.
The generative organs only attain maturity in the adult, which is, in fact, exclusively devoted to reproduction. No trace of testes is found in the larva, though the two dorsal splits from the walls of which the spermatozoa will arise are present. They are lined by a definite epithelium (Fig. 83), and this serves at once to distinguish them from the body-cavity. Posteriorly the splits narrow and become the two vasa deferentia which open one on each side into the cloaca. The cells lining the lumen give rise to secondary cells, and these become spermatozoa, the process extending from behind forwards. The external organs—bursa, etc.—described by Vejdovsky were not found by von Linstow.
Fig. 85.—Section through a mature female Gordius tolosanus. (From von Linstow.) Lettering as in Fig. 84; g, egg-sac; h, ovary.
Fig. 86.—Section through a female Gordius tolosanus when the deposition of ova is almost complete. a, b, c, d, e, and f, as in Fig. 84; g, egg-sac; h, ovary almost empty; i, dorsal canal containing eggs; j, receptaculum seminis.
In the female larva two similar splits are present; these form the egg-sacs. Posteriorly they end in two short oviducts which open into a uterus, in which fertilisation takes place, and in which the secretion arises which cements the eggs together. In the adult the ovaries and a receptaculum seminis are found, in addition to the organs present in the larva. The ovaries are formed from modifications of the packing tissue; they begin close behind the head, and soon attain such dimensions as to compress the egg-sacs and body-cavity to small slits. After a time the wall between the ovary and the egg-sacs becomes absorbed, and the eggs grow into the latter. In the old females, where the egg sacs are empty, there is a considerable space round the exhausted ovary, into which eggs continue to fall off; there is also a median dorsal canal which contains a few eggs. By this time the wall between the ovary and the egg-sac has again appeared.
One of the most interesting points about the female is that, according to Vejdovsky, the ovary is segmented, the cells which form the ova being heaped up in segmentally-arranged masses. This observation, if correct, is almost the only instance of segmentation recorded in the group Nemathelminthes.
