Io8 AMPHIMIXIS OR ESSENTIAL MEANING OF [XII. 



nogenesis by C. Th. von Siebold^ and Rudolph Leuckart^. 

 When it was understood that, under certain circumstances, an 

 ^gg could develope into a new individual without fertilization, 

 this fact by itself was sufficient to show that a ' vitalization of the 

 germ ' could not be the object of fertilization, and could not be 

 the cause of its appearance amiong living beings. 



But it was long before the facts of parthenogenesis were ge- 

 nerally accepted : indeed, in some circles they are not received 

 at the present day. Only ten years ago, a prominent physio- 

 logist, Pfliiger, held them to be unproved, and most botanists 

 were inclined to doubt their existence among plants as well as 

 animals ; for at that time parthenogenesis appeared to be 

 wanting in plants and to have been erroneously believed in at 

 an earlier date. Even when de Bary and Farlow had proved its 

 undoubted existence in certain ferns, and others had found it in 

 certain fungi, the Basidiomycetes, and the existence of parthe- 

 nogenesis among some plants and many animals could no 

 longer be denied, the attempt was made to crush the pheno- 

 mena in the Procrustean bed of the received conception of 

 fertilization. The ingenious French savant Balbiani had pre- 

 viously propounded the view that a certain occult and hitherto 

 undiscovered fertilization took place at the seat of origin of the 

 germs, in the ovaries and testes ; this fertilization was supposed 

 to be in addition to the regular, recognized process, and, in cases 

 of parthenogenesis, to compensate for it. So deeply rooted was 

 the idea that new life could only arise by means of fertilization. 



Even those investigators who no longer doubted the reality of 

 parthenogenesis could not immediately and completely rid 

 themselves of the received view, but endeavoured to make the 

 new facts harmonize with the old ideas. Probably the most 

 interesting attempt of this kind proceeded from Hensen, 

 who indeed recognized that the 'views on sexual reproduction 

 held up to that time had been overthrown ' by means of partheno- 

 genesis, inasmuch as the fundamental proposition as to sexual 

 propagation had failed, viz., that one of the two sexual cells is 

 by itself incapable of development. He nevertheless believed 



^ C. Th. von Siebold, ' Wahre Parthenogenesis'; Leipzig, 1856. 

 2 Rudolph Leuckart, ' Zur Kenntniss des Generationswechsels und der 

 Parthenogenesis bei den Insekten'; Frankfurt, 1858. 



