668 THE GENERATIVE ORGANS. 
the ovum which is situated at the posterior end of the egg-tube, 
or that nearest the convex surface of the ovary and the oviduct; 
the others, three or four in number, remain rudimentary, but 
are probably matured in succession after the mature ova are 
deposited (see p. 5). The most anterior chamber has been 
named the terminal chamber ; it is the smallest and most rudi- 
mentary. The membrana propria of the egg-tube is prolonged 
beyond the terminal chamber, and forms the terminal thread 
by which the egg-tube is connected with the peritoneal tissue 
of the concave surface of the ovary. 
The Relation of the Egg-tubes to the Oviduct.—The egg-tubes 
have no direct connection with the oviduct. If the fully- 
developed ovaries are removed from the insect, the egg-tubes 
can be easily separated from each other after the rupture of the 
capsule of the ovary. They then diverge from each other and 
assume a radial arrangement, only remaining attached to the 
capsule by the terminal threads. 
The relation of the egg-tubes to the oviduct is such that the 
ova can only be discharged into it by the dehiscence of the 
tunica propria of the egg-tube, and I have frequently found the 
empty remains of the membrana propria of the large egg- 
chamber attached to the rudimentary ova in the anterior part 
of the egg-tube after the discharge of the ovum from its 
interior. 
A large number of tracheal vessels are seen covering the 
external surface of the ovary ; those on its convex surface are 
very large, and have a stellate arrangement ; they arise from 
two or three large trunks, and give off numerous branches 
which ramify in the septal tissue of the ovary, and also minute 
branches which pass at once on to the egg-tubes. These small 
vessels fix the convex blind end of the egg-tube to the convex 
surface of the ovarian capsule. They are easily ruptured, and 
it is owing to this that the egg-tubes diverge from each other 
when the peritoneal capsule is ruptured. 
The Structure of the Ovaries in various Insects.—The ovaries 
of many Coleoptera, perhaps of all, and certainly those of 
Melée, which I have carefully examined, of many Hymeno- 
