[ 193 ] XIV. On the Agamic Reproduction and Morphology of Aphis. — Part I. By Tuomas H. Huxley, F.R.S., Professor of Natural History, Goternmeat School of Mines. Communicated by G. Busk, F.R.S., F.L.S. Read November 5th, 1857. § I . Pieliiiiinary Remarks. § 2. The Viviparous Female, and the Development of the Pseudova. § 3. The Oviparous Female, her Reproductive Organs and Ova. § 4. The Development of the Pseudovarium in the Viviparous Female. § 5. Summary; and Comparison of Germs and Ova. § G. Hypothetical Explanations of Agamogenesis. § 7. Classification of the Phenomena of Agamogenesis. § 1. Preliminary Remarks. " eJ'AI souvent pense qu'ou pourrait, dans I'histoire des sciences, designer les epoques par les principales decouvertes. Par example, 1665 seroit Vepoque de la. Gravitation ; 1789, Vepoque de la methode naturelle en Botanique ; et, si parva licet componere magnis, les annees 1740 a 1750 seroient Vepoque des Pucerons* " Without, perhaps, being disposed to go so far as the enthusiastic French investigator of Plant-lice, no physiologist will deny that the experiments conceived and attempted by E.6aumiu*, but first successfully carried out by Bonnet, established facts of the highest importance, and raised questions which still disturb the very foundation of his science. But what were these great facts, estalslished by Bonnet and his successors or contem-poraries, Trembley, Lyonet, Degeer, Kyber, and others ? If the moderns paid due attention to the labours of their predecessors, an accurate answer to this question should be found in every accredited text-book on zoology. But it will be found, on the contrary, that important errors have crept into the current con-ceptions respecting the reproductive processes and mode of Life of the Aphides, and that at the present day the state of general information as to the natural histoi-y of these smgular creatures is in many respects rather behind, than in advance of, that of the past generation. Bonnet's wonderfully patient and laborious researches t proved, beyond all doubt, 1st, that the viviparous Aphis may propagate without sexual influence ; 2ndly, that the l)rood 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 Aphides and tlieir brood may be either winged or apterous ; Ithly, 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 * DuTBu, MAn. du Museum, xiii. 1825. t Traitd d'Insectologie, 1745.
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