232 



THE AMEKICAN MONTHLY 



[December, 



alcoholic solution of some coloring 

 matter (logwood answers well) to the 

 alcohol in the tube. The subsequent 

 use of ether will fix the color. 



Usually after this treatment, the 

 object will be found to be quite clean ; 

 but if not, it should be gently brushed 

 with a camel-hair pencil while in the 

 turpentine or glycerin-fluid. The 

 wings of many insects are partially 

 destroyed during the process, but 

 since these can, if desired, be easily 

 mounted separately, this is not of 

 very great importance. 



The next point is how to mount 

 our objects without pressure. Small 

 insects, — such as ichneumon-flies and 

 gnats, — parts of insects, such as the 

 legs, etc., — leaves and other portions 

 of plants, may be mounted in shallow 

 cells, formed by running a ring of 

 gold-size or " brown cement " on the 

 glass slip. The brown cement is very 

 useful for this purpose, and is highly 

 recommended where a rapidly-drying 

 and firm cement is required. For 

 those to whom expense is no object, 

 the slips having cells hollowed out in 

 the centre should be chosen. 



Larger objects will need a deeper 

 cell than any of these afford ; and to 

 form such, vulcanite rings are un- 

 doubtedly the best, as also they are 

 the cheapest. A number of these 

 rings, of various thicknesses, should 

 be cemented to ground-edge glass 

 slips. Let no true microscopist in- 

 dulge in the paltry saving effected by 

 using slips with rough edges. Though 

 anyone possessed of such ultra- 

 frugality may have the right to cut 

 his own fingers with their sharp 

 edges, he has no right to endanger 

 the cuticle of his friends : and if he 

 intends to prevent this by covering 

 up the slide with some of the harle- 

 quin papers too often used, he will 

 find that there is no economy in the 

 double purchase, either in the matter 

 of time or expense. 



Having prepared a number of vul- 

 canite cells a day or so beforehand, 

 we select one just a trifle shallower 

 than the object to be mounted: and 



if the mounting is to be in any other 

 solution than Canada balsam or dam- 

 mar, we proceed thus: — The top edge 

 of the cell we cover with a thin layer 

 of brown cement ; then we breathe 

 into the cell, and before the moisture 

 dries fill it up with the solution for 

 mounting in. If we did not breathe 

 into the cell, there would probably 

 be an ugly rim of minute air-bubbles 

 clinging round its bottom angle. 

 Into the cell we now place our blow- 

 fly's head or other object, and with a 

 needle or small sable-brush arrange 

 it in the centre in any desired posi- 

 tion. Insects mount best by placing 

 them oh their backs. 



After seeing that the cell is brimful 

 with fluid, we take up a clean cover- 

 glass of such a size that it is not quite 

 so wide as the full width of the vul- 

 canite ring, and on the under side of 

 this we breathe gently: then quickly 

 place one edge downwards on to the 

 vulcanite ring, in the position it will 

 finally occupy, and somewhat slowly 

 lower down the opposite edge on to 

 the ring till the cover-glass lies flat. 

 If this is properly done, there will be 

 no air-bubbles in the cell, nor any 

 clinging to the cover-glass ; neither 

 will the object be forced from its 

 central position. To ensure the still 

 tacky cement fastening the cover- 

 glass securely, we place over the 

 whole a slight spring-clip, and leave 

 the mount thus for some hours. 

 Then the clip may be taken off, and 

 the slide washed under the tap; when 

 dry, a new ring of cement should be 

 placed on the edge of the cover- 

 glass and on the outer edge of 

 the vulcanite ring : to which any 

 rings of colored cement may 

 afterwards be added. There are 

 few finishing cements that are equal 

 in appearance, or so durable, as that 

 made by adding one-third of gold- 

 size to some Brunswick black : it 

 dries rapidly and is tough and elastic. 



For mounting in Canada balsam 

 or dammar, we make a similar ring 

 of brown cement on the vulcanite 

 ring. Inside the ring, or cell, we 



