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On Parthenogenesis, 405 



"Prof. Slebold, who in his ^Bemerkungen iiber Psychiden/ in the 

 * Jabresbericht der Schlesischen Gescllschaft,' ctc.» 1850, p. 85, appears to 

 have taken for granted that the self-fertile individuals of Talcsporia {Sole- 

 nobia) are, ' in ihrer organisation von weiblichen Thieren fjanz verschiedene 



orga 

 geschlechtslose Individuen^ (in their organization from tire female animals, 

 entirely different sexless individuals), in his latest and very interesting 

 essay, ' Wahre Parthenogenesis bei Schmetterlingen und Bienen/ admits 

 that the self-fertile individuals in these insects are true females, 



"This is also not the less evident in Daphnice ; for in them tiot only 

 may the same specimen produce first agamic eggs, then ephippial, then 

 again agamic, and then again ephippial eggs, so that it would have to be 

 considered first sexless, then female, then sexless then female again, but 

 actually, and that usually, the embryonic forms of both eggs are present 

 at the same time." 



''Throughout this paper I have applied the name of egrfs to the ordi- 

 nary reproductive bodies of the Daphnicej although aware that it is cus- 

 tomary to call all egg-like bodies which are fertile without immediate im- 

 pregnation internal buds' or 'gemmie,' and to consider them as essentially 

 diflerent from true eggs. Dr. Carpenter* and Dr. Burnettf have adopted 

 this theory, and iVI. de Quatrefages alsoj says, 'Seulement chez les der- 

 nieres [winged female Aphides, in opposition to the so-called sexless spec- 

 imens] on trouve de veritables ceufs, pourvus de toutes leurs parties 

 caracteristiques; chez les premieres de petites masses granulenscs, ou I'on 

 ne distingue jamais ni vitellus, ni vesicule germinative, ni tache de 

 Wagner.' 



In this statement he probably relies on the descriptions of J. V. Cams 

 and Dr. Burnett, but Leydig has already shown that there is good reason 

 for supposing them to be in error; at any rate it is by no means applica- 

 ble to the Daphnice. In these we find in the ovary a number of ovarian 

 masses containing small cells. One of these latter swells, dark granules 



collect around it, and it becomes a germinal vesicle. This is the founda- 

 tion of an ephippial egg. Just in front, another cell swells a little, be- 

 comes surrounded in a similar manner by dark granules, and also by oil- 

 globules, and this process continuing, forms the ordinary egg. I say e^^ : 

 for how can we deny this term to a round body developed in the ovary of 

 a female, and around a germinal vesicle? 



"Truly has M. de Quatrefages observed,§ * Ainsi Ton passe dela simple 

 croissance d'un manmiitere, au bonrgeonnement le mieux caracterise par 

 <Jes nuances insensiblcs: et tout nous raraene a cette importante conclu- 

 sion, que le bourgeonnement, et par cons6quent la reproduction agame, 

 ^^ sont au fond qu'un phenomene d'accroisseraent.* But why stop the 

 series here? Dr. Burnett says, indeed,]] that 'the structure and conditions 

 <>f all true ova are the same, and there is no passage between them and 

 buds ;' but this assertion is disproved by Leydig's observations on the 

 Aphides,^ and those now related in the Daphnice. Prof. Owen, on the 

 contrary, has maintained that buds and eggs are not bodies essentially 

 different in their nature, but that wo may expect to find every gradation 





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See Dr. Carpenter "On the Microscope and its Revelations;' p. 279. 

 Zoc, ciL X Loc. cit p. 121. § Zoc. cit p. ' 



2jOc, cit p. 8S. % Loc. cit 



