494 



TEXT-BOOK OF ENTOMOLOGY 



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 modifi- 

 cations of the male efferent ducts, or of the ovarian tubes, or (2) to 



a.g- 



FIG. 465. A, diagram of male sexual organs of Carabus. J>, of Blaps. C, of Hydrophilus. 

 The heavy black lines represent the ectodermal organs ; t, testis ; a. g., accessory glands. After 

 Escherich. 



various accessory organs, mostly glandular, resulting from the in- 

 vagination of the ectoderm. 



The male organs are, then, the following: 



1. Two testes (Figs. 465-469, *, H, ho}. 



2. The two seminal ducts (vasa deferentia, v, si, SL), whose lower 

 or outer (distal) division becomes enlarged and acts as a seminal 

 vesicle (vesicula seminalis; Figs. 467-469, bl, SB). 



3. The common ejaculatory duct (ductus ejaculatorius), with the 

 penis (Figs. 467-469, ag, uSGF). 



4. Accessory glands at the base of the vasa deferentia (glandule 

 mucosce, Figs. 465-469, a.g, dr, D), whose secretion mixes with the 

 semen or serves for the formation of the seminal packets (semato- 

 phores). 



