68 
BRITISH APHIDES. 
reproductive parts. In other terms, I propose to 
defend this thesis, that the oviparous Aphis partakes 
at the same time of the phenomena of both ordinary 
bisexual generation and hermaphroditism, which 
(latter ?) I consider to be the normal condition of the 
viviparous individuals of the same species ; or, if one 
prefers it, that they form, as regards their modes of 
reproduction, a bond of union between these last and 
other insects.’’ 
As might have been expected, these views elicited 
warm and energetic protests from many quarters. As 
long ago as 1799 Andrew Knight deduced from his 
experiments on interbreeding a general maxim, that 
it is a law of nature that organic beings shall not fer- 
tilise themselves in perpetuity.” Mr. Darwin also has 
most happily urged the same point on the attention of 
zoologists in*his researches on cross-fertilisation. Pro- 
fessor Mecznikow,^ in his ‘‘Observations on the Homop- 
tera,” in Siebold and Kolliker’s ‘Journal of Scientific 
Zoology,’ gives a concise history of the development 
of Aphides, and entered the lists foremost amongst 
the opponents of Balbiani’s hypothesis. He was fol- 
lowed by M. OlaperMe, who endorses Mecznikow’s 
opinion, “ that the doctrine of Hermaphroditism 
amongst Aphides is untenable.” I may remark that to 
me it is not easy to understand how such andro- 
gynous characters, if they really existed, could have 
escaped the acute observation of Von Siebold, Leuck- 
art, Huxley, and other physiologists. Pertinent to 
this subject, I may be allowed to state that up to the 
present time I have failed to obtain evidence in favour of 
Balbiani’s special views in any of those species which I 
have dissected. The subject will again be referred to 
when the anatomy of the reproductive organs of Aphis 
comes under discussion. 
In closing this short bibliography of Aphis, I will 
for greater precision quote M. Balbiani’s words, lest I 
Mecznikow, “ Untersucliiingen iiber die Embryologie der Hemi- 
pteren,” ‘ Zeitsclirift flir Wissensch. Zool./ t. xvii, 1866. 
