1892-93.] Mr A. B. Griffiths on Organs of Noctua pronuba. 101 
sac (fig. 3 illustrates these processes under high power). Near the 
base of the interior of the copulatory sac, a transverse triangular 
valve is suspended from above, which is also covered Avith the same 
kind of jDrocesses. 
Near the base of the vagina, a slender sperm-duct (fig. 1, /) 
passes from the vagina into the oviduct, through which the sper- 
matozoa pass from the copulatory sac, where they are discharged 
into the oviduct in which the ova are fecundated as they pass out- 
Avards. The sperm-duct does not expand into a spermatheca, as is 
the case in many insects. As already stated, the ova (fig. 5) are 
fecundated during their passage along the oviduct, and are then 
covered Avith the viscous secretion of the colleterial glands.* 
It may he stated that the ova of Noctua reach maturity at the 
close of the pupal state, and, consequently, they are ready for 
fecundation and oviposition as soon as the pupal skin has been cast.f 
In some Lepidoptera (as well as other Insecta), there are tAvo 
glandular organs, situated near the opening of the vagina, Avhich 
secrete an odorous substance that excites copulation, or, in other 
Avords, that attracts the males. These glands appear to be absent 
in the female Noctua pronuba ; in fact, the so-called “ scent organs ” 
are a distinctive feature of the male. 
BIBLIOGRAPHY. 
The literature on the reproductive organs of tlie Insecta is very extensive, 
consequently the following chronological list is far from being complete, but 
it gives the references to many important memoirs and Avorks on this and 
kindred subjects. 
Bonnet, “ Traite d’Insectologie,” 1745. 
Savigny, “Memoires sur les Animaux sans Vertebres,” 1816. 
Gade, “ Beitrage zur Anatomie der Insekten,” 1821. 
Latreille, “ Traite d’Insectologie,” 1825. 
Lyonet, “ Recherches sur I’Anatomie des Insectes,” 1832. 
Lacordaire, “ L’ Anatomie et la Physiologic des Insectes,” 1834. 
DuGbs, “ Traite de Physiologie Comparee,” 1838. 
Kulliker, “ Observationes de prima Insectoriim Genesi,” 1842. 
* The Auscous secretion of these glands hardens into a substance which gives 
the characteristic reactions of chitin. 
t In certain insects (e.(/., Libellula) the ova do not reach maturity until a 
later period. 
