2. All other parts of the efferent apparatus (uterus, vagina, receptaculum seminis, ductus ejaculatorius, penis, and appended glands) develop from the hypodermis.
3. The connective tissue and the musculature of the efferent apparatus are derived from mesoblast cells present in the body-cavity.
4. The efferent ducts originate as paired rudiments. All unpaired (azygos) parts (uterus, penis, receptaculum seminis, unpaired glands, etc.) are at first paired. The unpaired efferent apparatus of insects must therefore be regarded as morphologically a secondary and more complicated form.[[76]]
5. The male and female efferent ducts are strictly homologous.
6. The cavities of the oviducts, uterus, vagina in the female, of the vasa deferentia, appended organs, and ductus ejaculatorius of the male arise independently, and come into connection secondarily.
The presence of two genital openings, viz. a bursa copulatrix or copulatory pouch, and of the primitive oviducal orifice behind the 9th segment, is peculiar to Lepidoptera, and the inquiry naturally arises whether they represent the outlets of two pairs of segmental organs. The question has been fully set at rest, however, by Jackson, who shows that the copulatory pouch is a secondary invagination of the ectoderm, being derived from the hypodermis, while the second aperture is a special adaptation. It is, however, the partial homologue of the vaginal orifice in other orders of insects. It opens behind the sternite of the 8th abdominal segment, the typical position of the vaginal aperture as shown by Lacaze-Duthiers. The lateral position of the bursa and its separation from the azygos oviduct are probably late features in the phylogenetic history of the Lepidoptera, subsequent even to the closure of the furrow.
“The existence of a second or posterior aperture is probably to be attributed to the advantage gained by a terminal position for the aperture through which the ova are laid. The remarkable way in which this aperture shifts backwards seems to point very distinctly to this explanation, especially as the Lepidoptera are entirely devoid of the outgrowths which form the ovipositor in some orders; e.g. most Orthoptera.”
The original condition of things appears to have been retained in a moth, Nematois metallicus, which, according to Cholodkowsky, possesses but a single external aperture, the bursa opening into the dorsal wall of the unpaired oviduct.
a. The male organs of reproduction
Bearing in mind that the testes with their efferent ducts are, like the ovaries and egg-tubes, primitive structures, there are various secondary or adaptive structures which are either due (1) to modifications of the male efferent ducts, or of the ovarian tubes, or (2) to various accessory organs, mostly glandular, resulting from the invagination of the ectoderm.