402 On Parthenogenesis. 



mass ; and moreover after close microscopic investigation Mr. 

 Lubbock states that their formation appeared to commence from 

 a cell or germinal vesicle like the ephippial <dgg^ and differed 

 little apparently in the process of enlargement excepting in the 

 addition of one or more oil-globules. As the development pro- 

 ceeded, a very delicate membrane (vitelhne membrane) forms 

 about the egg. In about four days after a preceding brood had 

 been produced, another brood was ready to enter the receptacle, 

 the preceding having by this time developed sufBciently to swim 

 about freely in the water. Mr. Eubbock remarks concerning the 

 corresponding facts in the Aphides : 



"If we except the non-essential difference, that in Dapknia the devel- 

 oping eggs do not alter their place in the ovary, the whole process as noMT 

 detailed, is so similar to that which is described by Leydig in the Aphides, 

 as to confirm in a remarkable manner his observations, and on the other 

 hand, of course, to throw more doubt on the entirely different accounts of 

 J. V. Carus and Dr. Burnett. I must, however, confess, that like the two 

 last-mentioned observers, I have been quite unable to detect any germinal 

 vesicle in the eggs of the viviparous Aphides; it is, however, very diffi- 

 cult to find even in those eggs which are destined to be impregnated in 

 the ordinary manner, or indeed in any insect eggs, while, on the contrary, 

 1 have found it to be very largo in all the eggs of Crustacea which have 

 come under ray notice." 



Mr. Lubbock gives a brief notice of various papers bearing on 

 the subject of Paxthenogenesis, which we cite. 



"The Crustacea are so seldom bred and watched in captivity, that 

 although the Daphniadae is the only family in the class which is as yet 

 known to reproduce by parthenogenesis, yet the instances jpay hereafter 

 prove to be much more frequent, as the fact that no males have yet been 

 found of Polyphemus oculus, Limnadia gigas or Apics would seem to 

 suggest 



"Similar phenomena have been recorded by Dumeril,* and more re- 

 cently by Newman.f 



"In the Insects, excepting the celebrated case of the Aphides and^the 

 enera Ct/nips and Apophyllus^ as stated by Hartig^J whose assertions 

 ave been confirmed by the appearance of Cynips Ugnicola in great num- 

 bers in the soutliwest of England within the last year or two, where in 

 several thousand specimens not a male occurred;— ^with these exceptions, 

 I say, the phenomenon of parthcnogcnegis has as yet only been met with 

 ]Q the Lepidoptera, probably because this is the order most frequently 

 bred by collectors. 



"Pallas has observed this phenomenon in Enprepia casta; Bernoulli 

 in Gastropkaga potatoria and Episema cceruki^ephola ; Easier in ^• 

 ^Mrcifolia; Suckow in Q. pini ; Treviranus in Sphinx ligustriy and 



* Acari6mie des Sciences, 28th Sept. 1856. . 



t An Essay on the employment of Physiological Characters in the Classification 

 of Animals. 



1 Germar's Zeitschrift, toL ii. d. 178. 



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