COLLECTIONS OF INSECTS, ETC. 175 



Those who use a separate card for each specimen adopt the 

 plan of numbering each and keeping a book of reference. The 

 objection to this method is that very soon the number of speci- 

 mens becomes so enormous, and the entering in the reference- 

 book takes so much time, that it is soon discontinued. One 

 reason why separate cards are used is because it is often difficult 

 to determine whether several specimens are really of the same 

 species. They are, therefore, mounted singly, and put aside for 

 consideration at some future time, whereas if they are to be asso- 

 ciated together on the same card, this point must be decided at 

 once. This is, I think, rather an advantage than a drawback, as 

 these difficult points get cleared up at once instead of being put 

 off and forgotten, and perhaps never properly worked out at all. 



I now come to the points to which I feel many collectors 

 would object. I think we ought also to have specimens mounted 

 in such a form that they can be placed on the stage of the micro- 

 scope at once, and at the same time to be so protected that they 

 may not get injured by repeated handling and examination. This 

 object, it seems to me, may be attained by mounting the insects 

 on the usual three-by-one inch glass slips in a dry cell as solid 

 objects. After trying various kinds of cells, I found nothing at 

 that time better than cardboard, punched out with a gun-punch, 

 and stuck on with gum-tragacanth, to which some drops of car- 

 bolic acid had been added. The cells were made of the required 

 depth by building up, piece upon piece, as many thicknesses of 

 card as were necessary, and when dry the inside of the cell was 

 brushed over with benzole, containing about lo per cent, of car- 

 bolic acid. The insects were placed in the cells, and attached 

 with the smallest quantity of gum-tragacanth, and, if not too deli- 

 cate, such as the green weevils, were lightly brushed over with 

 benzole. This removes grease, which is a condition Beetles are 

 very likely to assume, and effectually prevents the growth of 

 fungi. The precaution was also taken, before putting on the 

 cover-glasses, to place the slides in a moderately hot oven for a 

 short time, so as to ensure their being quite dry. They were then 

 covered with coloured paper in the usual way, and distinctly 

 labelled, marking not only the name and locality of the specimen, 

 but the peculiarity, if any, which the particular slide was intended 



