ON THE AGAMIC REPRODUCTION AND MORPHOLOGY OF APHIS 27 
every accredited text-book on zoology. But it will be found, on the 
contrary, that important errors have crept into the current concep- 
tions respecting the reproductive processes and mode of life of the 
Aphides, and that at the present day the state of general informa- 
tion as to the natural history of these singular creatures is in 
many respects rather behind, than in advance of, that of the past 
generation, 
Bonnet’s wonderfully patient and laborious researches! proved, 
beyond all doubt, Ist, that the viviparous Aghzs may propagate 
without sexual influence ; 2ndly, that the brood thus produced may 
give rise to young in the same way; that these may repeat this 
asexual prolification ; and so on, for as many as ten broods; 3rdly, 
that the viviparous Apfides and their brood may be either winged 
or apterous; 4thly, that, under certain conditions, winged or wingless 
males appear and copulate with oviparous females, which, in the 
instances observed by Bonnet, were wingless. 
These are the statements put forth by Bonnet on the evidence 
of direct observation and experiment, and they have been confirmed 
by every subsequent original observer whose works I have perused. 
Besides these matters of fact, Bonnet states, as his strong opinion, 
that there is no fixed limit to the process of agamic, viviparous 
reproduction, and that, under favourable conditions of warmth and 
nourishment, it might be continued for “thirty generations” (/. c. 
p. 102), or, in other words, indefinitely. 
The accurate and painstaking Degeer, who gives an elaborate 
account of some seventeen species of Ap/zs, affirms, as the result of 
his researches, “that the winged -phides are never oviparous.”*? He 
describes at length the apterous males of certain species (P. lisse du 
Pin, P. du Pommier, P. du Genévrier), and shows that apterous, ovi- 
parous, and winged viviparous broods may coexist, as in Aphis Kose. 
Degeer considers that, as a general rule, the oviparous females 
and the males are produced by alate viviparous females. 
The next important original memoir on the Apfzdes is that pub- 
lished in Germar’s ‘ Magazin der Entomologie’ for 1815, by Kyber,* 
evidently a most careful observer, but somewhat wanting in method 
and clearness as a writer. Kyber is in perfect accordance with 
Bonnet and Degeer ; and, more than this, he experimentally proved 
the justice of Bonnet’s supposition, that the duration of the agamic 
1 Traité d’Insectologie, 1745. 
’ Degeer, Mém. sur les Insectes, 1774, vol. lil. p. 74. 
3 Einige Erfahrungen und Bermerkungen tiber Blattlause von J. F. Kyber, Diacon. in 
Eisenberg. 
