INTERNAL ANATOMY OF INSECTS. 165 
actual contact of the sperm with the eggs, but of some un- 
known sympathetic influence*, or rather perhaps of some 
penetrating effluvia or aura seminalis, which, though 
small in quantity, it may retain the power of emitting for 
a long period. 
Certain female moths, of the species of that family 
which, from the remarkable cases or sacs the larva? in- 
habit, the Germans call sack — trliger; before noticed b , 
have been supposed to have the faculty of producing fer- 
tile eggs without any sexual intercourse ; and various 
observers, after taking great pains, appeared to have sa- 
tisfactorily proved the fact; so that some doubted whether 
these insects produced any males at all c . The enigma 
was at length explained by the accurate Von Scheven 
At first his experiments were attended with the same 
suit as those of his predecessors; but upon making them 
more carefully, and separating what he conceived to be 
the female from the male pupae, he ascertained not only 
the existence of a female in the species he examined 
(Psyche vcstita), but that when thus secluded she laid 
barren eggs ; evidently proving that in the contrary in- 
stances above alluded to, an unperceived sexual inter- 
course must have taken place d . Though he thus ascer- 
tained that these insects do not in this respect deviate 
from the general rule, he remarked or confirmed several 
facts in their economy sufficiently anomalous and strik- 
ing ; — as that the female is not only without wings, but 
with scarcely any feature of a moth, much more closely 
resembling a caterpillar; and that in ordinary circum- 
n Philos. Trans. 179/. 80. b Vol. I. p. 461. 
r Compare Reaura. iii. 153. Pallas Act. Nat. Cur. 1767. i". 430. 
Wien. Verzekh. 292. d Naturfor St k . xx. .59—. 
