CONCLUDING REMARKS. 105 



Of the genus Cynips, twenty- eight species are known, which, 

 according to Hartig's statement, are all destitute of males*. 

 Hartig has inspected nine or ten thousand of Cynips divisa, and 

 three or four thousand of Cynips folii, and found no single male 

 amongst them. Hartig has even collected Cynips folii for eight 

 years, and has never obtained anything but females of this Gall- 

 fly ; at the same time he saw these female Cynipidce proceed to 

 the deposition of their eggs immediately after their issuing from 

 the galls. 



The reproduction occurring amongst certain of the lower 

 Crustacea, which it has been attempted to refer to Alternation of 

 Generations and nurse-formation, may also turn out on closer 

 investigation as true Parthenogenesis. As is well known, the 

 genus Apus amongst the Phyllopoda only presents females ; 

 Zaddach indeed has supposed that he discovered male indivi- 

 duals in Apus cancriformisf, but I have called this statement in 

 question, on account of the want of positive proof J. Of the 

 Phyllopodous Limnadia gigcis also, no male has yet been dis- 

 covered §. In Daphnia too, it appears not to be nurses but 

 female individuals which perform the business of reproduction 

 by Parthenogenesis ; for Lievin, who has compared with each 

 other, female Daphnia taken in copulation, and others which 

 were independently prolific, could not find the least distinction 

 between the two kinds ||. Of Polyphemus oculus, we as yet only 

 know female individuals^. 



fecondation, quoique je procedasse a leur vivisection immediatement apres 

 leur sortie de la galle." 



* See Zweiter Nachtrag zur Naturgeschichte der Gallwespen in Germar's 

 Zeitschrift fur die Entomol. band iv. 1843, p. 397. 



f See Zaddach, De Apodis cancriformis anatome, 1841, p. 53. 



X See my Lehrbuch der vergleichenden Anatomie der wirbellosen Thiere. 

 1848, p. 495. note 8. 



§ See Brongniart, Memoire sur la Limnadia, in Memoires du Museum 

 d'Histoire Naturelle, toni. vi. 1820, p. 89. " II reste un point tres curieux it 

 e'claircir dans l'histoire de ces anitnaux, c'est leur mode de generation ; il est en 

 effet fort remarquable que sur pres de mille individus que nous avons vua a 

 Fontainebleau, tous portoient des ceufs soit sur le dos, soit dans le corps.*' 



|| See Lievin, Die Branchiopoden der Danziger Gegend, in the Xeuesten 

 Schriften der Naturforschenden Gesellschaft in Danzig, band iv. heft. 2, 1848, 

 p. 26. 



IT See Jurinc, Histoire des Monocles qui se trouvent awe environs de Center. 



