102 BBITISH APHIDES. 



more convenient to insert between the glass slip and 

 its cover, than circles of card which are sometimes 

 recommended. The thin sheet lead from the Chinese 

 tea-chests is very suitable for punching, and as it is 

 not porous like card, it yields no air-bubbles by 

 heat. 



Herr D. von Schlechtendal has, in the ' Entomo- 

 logische Nachrichten,' iv, p. 155, described a method, 

 by which it would appear that all the characters of form 

 and colour (?) may be preserved in Aphides and other 

 insects. The method consists of a rapid death and 

 drying of the insect by means of a current of heated 

 air. The Aphis, previously attached to some suitable 

 support, is suddenly and momentarily subjected to the 

 heat of a spirit or other flame, by which it is imme- 

 diately killed and caused to retain its natural position. 

 Several examples are then carefully roasted in a 

 current of hot air, such as that passing through an 

 inclined glass tube, duly made hot, or dried on a sheet 

 of paper moved over a heated metal plate. 



When dry, the specimens are mounted on card by 

 attachment with gum-tragacanth ; or, as Mr. T. \\ r . 

 Douglas suggests, more conveniently on mica, called 

 11 talc " in the shops, which, as it is incombustible, is 

 well suited for a support both before and after drying. 



This method is vouched for as good by Drs. Giebel, 

 Taschcnburg, Mayr, and Rudow. 



I have not tried this roasting process, but it must 

 require some address to prevent the shrivelling of 

 wings in such delicately formed insects, and to provide 

 against the bursting action of the boiling juices. 



A more complete history of the process, than the 

 foregoing, was given by Mr. T. Douglas in 1878.* 



M. Lichtenstein has many times been good enough 

 to forward in Letters to me preparations of Aphides 

 which have been secured between two films of mica. 

 The insects, he explains, are immersed in a solution of 

 resin in turpentine, "a natural amber," and, when all 



* ' Eut. Mouth. Mag.,' vol. xv, p. 164. 



