THE ANNALS I MAGAZINE OF NATURAL HISTOUY. [SECOND SERIES.] No. 80. AUGUST 1854. VII. — Researches on the Development of Viviparous Aphides. By Waldo I. Burnett, M.D., Boston*. Every naturalist is aware of the remarkable phsenomena con-nected with the viviparous reproduction of Aphides or plant-lice, for their singularity has led them to be recounted in works other than those of natural science, and, from the days of the earlier observers, they have been the theme of a kind of wonder-story in zoology and physiology. I need not here go over the historical relations of this subject. The queer experiments and the amusing writings of the old ento-mologists are well known. The brief history of the general con-ditions of the development of these insects is as follows : — In the early autumn the colonies of plant-lice are composed of both male and female individuals ; these pair, the males then die, and the females soon begin to deposit their eggs, after which they die also. Early in the ensuing spring, as soon as the sap begins to flow, these eggs are hatched, and the young lice immediately begin to pump up sap from the tender leaves and shoots, increase rapidly in size, and in a short time come to maturity. In this state it is found that the whole brood, without a single exception, consists solely of females, or rather and more properly, of individuals which are capable of reproducing their kind. This reproduction takes place by a viviparous generation, there being i^med in the individuals in question young lice, which, when cap^le of enter-ing upon individual life, escape from their progenitor and form a new and greatly increased <;olony. This second generation pur-sues the same course as the first, the individuals of which it is composed being, like those of the first, sexless, or at least without any trace of the male sex throughout.* These same conditions are then repeated, and so on almost indefinitely, experiments having shown that this power of reproduction under such circum-* From Silliman's American Journal for January 1854. Ann. <Sf Mag, N. Hist. Ser. 2. Vol. xiv. ' 6
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