INTERNAL ANATOMY OF INSECTS. 165 



actual contact of the sperm with the eggs, but of some un- 

 known sympathetic influence 1 , 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 larvae in- 

 habit, the Germans call sack tr'dger, 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 vestita), 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- 



a Philos. Trans. 1797. 80. b VOL. I. p. 461. 



r Compare Reaum. iii. 153. Pallas Act. Nat. Cur. 1767. iii. 430. 

 Wicn. Vcrztich. 292. rt Xaturfor St k . xx. 59 . 



