VII PARTHENOGENESIS 261 



of the species, and the distinctive characters with 

 regard to these little moths, have occupied a great 

 deal of our author's time and attention, and are here 

 recorded. In regard both to Psyche and Solenobia 

 examination with the microscope was employed to 

 determine the absence of male elements from the 

 receptaculum seminis ; and we have moreover an 

 account of the structure of the ovaries. In relation 

 to this matter. Professor Siebold takes the opportunity 

 of replying to some criticisms of his former work by 

 M. Plateau, who appears to have made little of the 

 arguments based on the proof thus obtained of virgin- 

 ity, without knowing the real extent and nature of 

 Siebold's studies, having, in fact, only read of them 

 in an imperfect abstract. It appears also that M. 

 Plateau took " ein einziger Fundort" to mean "un 

 naturaliste collecteur," an amusing mistake to wdiicli 

 our attention is drawn in a note, p. 155. We may 

 briefly mention here with regard to Solenobia, that it 

 appears that S. lichenella is only the female brood 

 of S. pineti, of which males and females regularly 

 occur. No structural difl'erence appears to exist 

 between the two kinds of females, but the former, 

 on escaping from the chrysalis - sac, at once proceed 

 to lay eggs, which produce invariably females ; whilst 

 the latter wait for copulation, and if that be with- 

 held, die, and dry up without laying their eggs. 

 These insects ofl'er most promising material for further 

 researches on the conditions attending the difierentia- 

 tion of sex. 



AYe now come to the sixth and last chapter, on 



