INSECTS. 269 
with in most Insects and which unite with the efferent canal. That 
these parts rather serve to effect special secretions and correspond 
with the prostate and CowPsr’s glands in higher creatures is pro- 
bable even from their composite structure and great development. 
Hence in some Insects they have been even described as testiculd 
and the true testes as glands of an unknown use, as for instance, by 
SWAMMERDAM in Oryctes nasicornis!. In this and other Lamelli- 
cornia (Melolontha, Cetonia) these glands are two tortuous canals, 
which resemble the testiculé of the Carabicit. In Hydrophilus piceus 
these parts exceed the testes in circumference. Ordinarily there is 
one pair?: often also there are two pairs of these accessory organs 
present; in some are found three or even more pairs. They are 
entirely absent only in few Insects (Gersds, Velia, Ranatra). In 
Libellula they are also wanting®; yet I think it is nearer the 
truth to say that here they are not connected with the testiculd 
and are present in an unusual situation, which is in agreement with 
the copulation of these animals‘. From this also it is apparent that 
these organs are not vesicule seminales. 
For determining the purpose of the different parts connected 
with the organs of propaga ion microscopic investigation in the 
recent state is of great service. C. TH. Von Srepoup’ has never 
met with spermatozoa in the parts which we consider subservient to 
special secretions, which however they ought to contain if they 
were really seminal vesicles as Leon Durour and other writers 
suppose. The spermatozoa of Insects are like hairs, and are often 
found in the testes united in bundles and surrounded by a transpa- 
rent covering’, 
We must notice, in addition, that in many species of Insects a 
great similarity of form has been observed between the organs of 
propagation in the two sexes. We see this resemblance in certain 
1 Bijbel der natuur. Tab, xxx. fig. 8, m m; these are the true testes. I could almost 
suppose that L&on Durour so indefatigably laborious in the anatomy of Insects and 
so rich in experience, has made the same mistake in Pelogonus ; see the Rech. sur les 
Jlémipt. Pl. Xt. fig. 137 A., where I consider the spiral organs 6 } to be testes. 
2 As in the Hymenoptera, for instance. 
3 Léon Durour, Mém. présentés, vu. p. 572. 
4 See below, in the systematic arrangement, in the family of the Libellulina. 
5 See Von Srepoip, Ueb. die Spermatozoen der Crustaceen, Insecten, Gasteropoden 
u. einiger anderen wirbellosen Thiere, MUELLER’S Archiv, 1836, s. 1o—43, Tab. 1, 
