1878.] 165 



placed beneath the insect, on which the legs should be set out in the desired position. 

 But with some objects, such for instance as a young Strachia, the drying proceeds 

 very quickly, so that if distention be not observed then the heat is too great, for 

 the expansion of the air inside will force oiJ the head with a loud report ; also with 

 softer, thicker Pentatomidce care must be taken to begin with a heat only so strong that 

 the internal juices do not boil, for in such case the preparation would be spoilt. It 

 is of advantage to remove the cylinder from time to time and test, by means of a lens, 

 if a contraction of the skin has taken place on any part, if so the roasting is to be 

 continued. The desired hardness may be tested with a bristle or wire. 



For Aphides. The living Aphis is to be put on a piece of white paper, and at 

 the moment when it is in the desired position it is to be held over the flame, and in 

 an instant it will be dead and will retain the attitude. Then put it, still on the paper, 

 into the oven ; or, still better, hold it over the heated tin, carefully watching the drying 

 and moving the paper about in order to prevent it getting singed. The roasting is 

 quickly accomplished in either way, but somewhat slower out of the oven, especially 

 in the larger kinds, such as Lachnus. If the paper turn brown it is a sure sign that 

 caution is requisite. To pierce these brittle preparations for preservation is hazardous, 

 and it is a better way to mount them with gum on card, placing some examples on 

 their back. 



For CecidomyicB, AgromyzcB, Cynlpidce, and other small insects liable to shrink, 

 yet containing but little moisture, uch as Fodurce, Pedicidi, Psyllidce, &c., another 

 method is adopted. Over the insect, mounted on a wire, &c., as above directed, a thin 

 chemical re-agent glass, or glass rod, heated strongly at one end, is held, and the heat 

 evolved is generally sufficient to bring about the immediate drying and distension, 

 but if the heat be too little the process must be repeated ; and although by this 

 method the danger of burning is not obviated, yet the position of the legs is main- 

 tained much better than by the aforesaid roasting. 



Larvae of all kinds, up to the size of that of Asfyiiomus adilis, even when they 

 have long been kept in spirits, may be treated successfidly by the roasting method ; 

 but with these objects care mvist be taken that the heat is not too strong or else the 

 form will be distorted. For small larvae it is preferable to use a short glass, in order 

 better to effect their removal without touching the upper part, which becomes covered 

 with steam, and contact with which would cause the destruction of the preparation. 

 Larvae of Coleoptera, which contain much moisture or have a mucous surface, must 

 lie on a bed of paper or pith in order to prevent adhesion and burning, and these 

 may be further avoided if the cylinder be slightly shaken during the process, and the 

 position of the object be thereby changed. 



I have not had an opportunity of trying the roasting process, but it does not 

 seem to be difficult in any of its modifications, and with practice and care woidd be- 

 come easy. It is admitted that with slender-limbed insects the joints are rendered 

 very brittle, but practically this condition can hardly be worse than that which 

 results from ordinai-y drying. I would suggest the trial of pieces of talc —an incom- 

 bustible transparent material — cut into appropriate sizes, and that on these the 

 insects should be fixed in proper position by means of gum tragacanth (thus dispen- 

 sing with the wire). I think that the drying would be facilitated, and the talc might 

 remain as a permanent support and be fixed in the cabinet in the manner suggested 

 by Mr. Edwards, vol. xiii, p. 282.— J. W. Douglas, 8, Eeaufort Gardens, Lewisham : 

 November 13th, 1878. 



