MOUNTING INSECTS. 305 



tion. 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. J. W. Douglas suggests, more conven- 

 iently on mica, called ' talc ' in the shops, which, as it is incombusti- 

 ble, is well suited for a support both before and after drying 1 . 



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

 Mayer, 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. Douglas in 1878. 



" M. Lichtenstein has many times been good enough to forward in 

 letters to me preparations of Aphides which have been secured be- 

 tween two films of mica. The insects, he explains, are immersed in 

 a solution of resin in turpentine, ' a natural amber,' and, when all are 

 in due position, the mica films are placed over apertures in card, and 

 then gummed papers, similarly perforated, are pressed upon them. 

 This arrangement secures all in their places. 



"Methods and operations in science, like events in history, repeat 

 themselves. Fifty years ago films of mica were used to cover objects 

 for the microscope, and before the manufacture of the thin glass now 

 so commonly used it admirably answered its purpose. Under deep 

 magnifying powers, such as % in., it will be found even now of 

 great service. The mineral may be split by the lancet into films 

 much thinner than glass can be blown in a fiat state. Small un- 

 scratched pieces may be selected which are perfectly transparent, and 

 their cost is quite trifling. 



" On account of the high refracting power of Canada balsam, the 

 colors of recently-immersed Aphides show themselves very brightly; 

 and it sometimes happens that tints, quite lost through irradiation or 

 glance on the surfaces, become distinct by treatment with this resin. 



" The bright colors and markings of some species are due to the hue 

 of the internal juices of the insects. These cannot be preserved by 

 balsam, but it is otherwise with the pigments which stain the some- 

 what horny coverings of the thorax and abdomen. These colors are 

 persistent." ("Monog. British Aphides," iv. (1883) pp. 188-93.) 



Thomas W. Starr's Method of Preparing and Mounting, with Pressure, 

 Insects Entire as Transparent Objects.* After procuring the insect, 



* This, with the three following notes, were kindly communicated 

 by N. N. Mason, Esq. 



