OF GENERATION. 313 



copulated. Thus the Aphis has a companion in its great and highly 

 remarkable fertility. 



205. 



In the same way as a spontaneous generation is found as an excep- 

 tion among insects do we find imperfect hermaphroditisrn among them. 

 Perfect hermaphrodites among animals are found only in the tape- 

 worms, the Trematodes, many Annulala (for example, the leech and 

 earth-worm), and the majority of the Mollusca. They possess male 

 and female organs, but never impregnate themselves (perhaps with the 

 exception of the tape-worms), but mutually. In insects, on the con- 

 trary, hermaphroditism is but one-sided, that is to say the one, gene- 

 rally left side, exhibits female forms and organs, and the opposite side 

 male organs. Among the numerous instances of this kind the majority*, 

 indeed almost all, are found amongst the Lepidoptera, and thus this 

 order displays itself a second time as that which has the greatest 

 tendency to diverge from the regular sexuality of insects. 



The earliest observations upon this subject were made known by 

 SchiifFer in a separate treatise t- It was an hermaphrodite Liparis 

 dispar, O., the right side of which was male and the left female. Then 

 Scopoli described an instance in Gastrophaga Pini : according to his 

 account, two caterpillars had enclosed themselves in one cocoon, and 

 changed into one pupa, which produced an hermaphrodite imago, of 

 which one larger side was female, and the other, smaller, had male 

 wings and more strongly pectinated antenna, at the anus there were 

 both sexual organs, which copulated, after which the female side laid 

 eggs, from which young caterpillars proceeded. Henceforward com- 

 munications of this kind became more numerous. Esper next 

 described an hermaphrodite Gastrophaga Crattegi, in which the right 

 side was male and the left was female ; then Hettlinger || a similar one of 

 Gastrophaga Quercus ; Capieux ^[ saw an hermaphrodite of Saturnia 



* Consult Rudolph! iVber Zvvitterbildung in the Abhandlungen der Konigl. Academic 

 zu Berlin. Physkalischeiklasse, 1828, p. 50. 



f- Der wunderbare und vielleicht in der natur noch nie erschienene Eulenzwitter. 

 Regensb. 1761, 4to. 



Introductio ad Hist. Nat. Prag, 1777, 8vo. p. 41(j. 



Beobachtungen an einer neuentdeckten Zwitterphalane (Bombyx Cratcegi*). Erlangen, 

 1778, 4to. Schinetterlinge, vol. iii. p. 233. PI. XLV. f. 16. 



|| Rozier, Obs. dc Phys. torn. xxvi. p. 270. 



ll Naturforscher St. .\ii. p. 72. PI. II. f. H 



