246 PAETHENOGENESIS VII 



researches of Leydig (antecedent to Siebold's work in 

 some cases), Huxley, Lubbock, and Leuckart, on the 

 structure of the supposed buds of Aphis and allied 

 insects, and of lower crustaceans, proved that these 

 bodies were morphologically ova — originating in 

 ovaries, and having the essential structure of fertilisable 

 ova. For them the term " pseudova " w^as introduced 

 by Professor Huxley, since they differ in this respect 

 from other ova — that whereas the latter can be, and 

 are in most cases (though with constant exceptions), 

 fertilised, the latter cannot be.^ Whilst, then, up to 

 this period such a thing as parthenogenesis appeared 

 to be a strange exception, the question has now shifted, 

 and, since the essential identity in reproductive power 

 of cuttings, buds, pseudova, and eggs is proved, the 

 problem before naturalists is rather " Why are eggs 

 ever fertilised ? " in short, " What is the use of the 

 male sex at all ? " We have animals and plants mul- 

 tiplying by fission, breaking up into two or more parts, 

 each of which becomes a new individual ; we have 

 them giving rise by growth to masses of cells, which 

 become detached or remain attached, and develop each 

 into a new individual ; and finally, we have them ela- 

 borating single large cells, which become detached and 



^ Leuckart lias more recently proposed, in describing tlie reproduc- 

 tion of tlie Cecidomyia larvpe discovered by Wagner, to limit tlie term 

 ' ' pseudovum " to sucli ova as those produced by larvae, or imperfect 

 forms ; and not to apply it at all to the eggs of bees, wasps, etc. (which 

 can develop without fertilisation), as was done by Huxley. The falsity 

 implied in the prefix seems to make a rather stronger distinction than 

 is desirable between any of these bodies ; for they are all truly ova, 

 though ova of various special properties. 



