224 
SIEBOLD, ON PARTHENOGENESIS. 
the term Parthenogenesis^ and calls it "true Partheno- 
genesis/^ It is^ we thinkj to be regretted that the German 
Professor has thus attempted to apply a term_, invented by 
Professor Owen^ to another and different set of cases^ denying 
its applicability to the instances for which it was invented. 
We give Von Siebold's explanation of the facts as they occur 
amongst Aphides : 
" Not to deviate too far from the object which I have set before me in 
these pages, I will only here give prominence to that in the history of 
insects which people have been induced to regard as a peculiarity of the 
alternation of generations — I mean the remarkable reproduction of the 
Aphides ; this, after standing so long as something quite abuormal and in- 
explicable, has now found its complete explanation in the nature of the 
alternation of generations. It is well known that in the Aphides, a sexual 
generation, represented by separate males and females, is followed by a 
series of generations, only including a single form, which proceed from each 
other in manifold repetition without any previous copulation, until after about 
seven to eleven such generations, a generation of males and females again 
makes its appearance. Steenstrup regarded these forms of Aphides, which 
are capable of reproduction without the influence of the male generative 
organs, and which had previously been looked upon as virgin female Aphides, 
as nurses {Ammen)^ and consequently as those members of an animal species 
subjected to an alternation of generations, which are capable of producing 
young in the asexual (or larval) state. Those Aphides which bring forth 
living young without a preliminary copulation, are in reality quite different 
in their organization from the true female Aphides, which lay eggs capable 
of development after the act of copulation. In the viviparous Aphides 
those organs especially from which the living young are produced, have 
quite a different form and organization from the sexual organs of the ovipa- 
rous female Aphides, so that, in opposition to the ovaries {JEierstocke), the 
products of which (eggs) only become capable of development by the action 
of the male semen, we may with perfect justice indicate these organs as 
germ-stocks {Keimstbcke)^ which are capable of producing young of them- 
selves, without the influence of male fertilizing organs. These nurse-like, 
viviparous Aphides therefore, which instead of ovaries bear germ-stocks in 
their interior, are also destitute of the seminal receptacle, which occurs 
universally in the females of insects and plays an important part in the act 
of fecundating the eggs. Before the alternation of generations had yet 
been introduced into science by Steenstrup, I had already called attention 
to the different conditions of organization in the oviparous and viviparous 
Aphides, and especially to the absence of the seminal receptacle in the latter. 
Subsequently the development of the Aphides without fecundation has been 
completely explained by Y. Carus as a process of the alternation of gene- 
rations. The representation which Carus has given of the development of 
germinal bodies in the germ-stocks of the viviparous Aphides, has certainly 
met with a refutation from Ley dig, against which I have nothing to object ; 
nevertheless, although, according to Ley dig, the young are developed from 
the germ bodies of the viviparous Aphides exactly as from eggs, by cell- 
formation, I would retain the denominations germ-body" and "germ- 
stock " for these reproductive organs of the viviparous Aphides, in order to 
distinguish them, on account of their different physiological import, with 
regard to the alternation of generations, from the eggs and ovaries of the 
oviparous female Aphides. 
"Owen has regarded the asexual viviparous Aphides as virgin females 
