216 NOTICES OF SERIALS. 



Royal Institution of Great Britain. Miscellaneous — (Dr. Garreau) On the 

 Formation of the Stomata in the Epidermis of the Leaves of the Spiderwort, and on 

 the Evolution of the Cells in their Neighbourhood ; (H. and A. Adams) Descrip- 

 tion of a New Genus of Bivalve Mollusca ; (M. Tulasne) On the Dimorphism of 

 the Uredineae. 



No. 80, August: — (W. J. Burnett, M.D.) Researches on the development of 

 Viviparous aphides. This paper is extracted from Silliman's American Journal 

 for January, 1854, and being of the greatest interest, we give large extracts in 

 the author's own words : — " Every naturalist is aware of the remarkable pheno- 

 mena connected 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 his- 

 torical relations of this subject. The queer experiments and the amusing writings 

 of the old entomologists are well known. The brief history of the general condi- 

 tions 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 

 egg3 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 formed in the individuals in question, young lice, which, 

 when capable of entering upon individual life, escape from their progenitor and 

 form a new and greatly- increased colony. This second generation pursues 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 hav- 

 ing shown that this power of reproduction, under such circumstances, may be exer- 

 cised, according to Bonnet, at least, through nine generations ; while Duvau ob- 

 tained thus eleven generations in seven months, his experiments being curtailed at 

 this stage, not by a failure of the reproductive power, but by the approach of winter 

 which killed his specimens ; and Kyber even observed that a colony of Aphis 

 dianthi which had been brought into a constantly-heated room, continued to propa- 

 gate for four years, in this manner, without the intervention of males, and even in 

 this instance it remains to be proved how much longer these phenomena might 

 have been continued." We have then described the various observations of Dr. 

 Burnett on the Aphis Caryae of Harris, and the details of the embriological deve- 

 lopment of the so-called Viviparous aphides, so far as our author had enjoyed op- 

 portunity for their study. M We will now refer for a moment to the special points 

 which have here been made out. In the first place, it is evident that the germs 

 which develop these forms are not true eggs. They have none of the structural 

 characteristics of eggs, such as a vitellus — a germinative vesicle and dot ; on the 

 other hand, they are, at first, simple collections, in oval masses, of nucleated cells. 

 Then, again, they receive no special fecundating power from the male, as is the 

 necessary preliminary condition of all true eggs ; and, furthermore, the appearance 



