1880.] 



MICKOSCOPICAL JOUKNAL. 



233 



white worm, with strong black man- 

 dibles, which led me to think that 

 the worm got many a dainty meal 

 from the insects that were caught. 

 When I have collected them late in 

 the season, I have found a hole near 

 the bottom of the tube which I was 

 led to think the worm had made to 

 get out. But how the warm got 

 there I am at a loss to know. I be- 

 lieve the worm is the larva of some 

 insect. 1 have taken them out, and 

 have examined them under the mi- 

 croscope while living, and I have 

 dried one, and have it now mounted 

 as a microscopical object. 



Mounting Opaque Objects. 



We have seen a good deal lately 

 on the subject of dry mounts and 

 the use of wax-cells, and the latter 

 are almost universally condemned 

 now, though within a year or two 

 a great many methods for mounting, 

 in which wax is used, have been 

 described. I have tried every one 

 of these methods, but have given 

 them all up, and now use nothing 

 but cells cut out of different thick- 

 ness of tin-foil, and finished on a 

 lathe. My method of mounting is 

 as follows : The object is first fast- 

 ened to the slide, which is centered 

 on the tum-table, by means of a 

 weak solution of gelatin, gum- 

 water, or Brunswick black. For 

 very small objects a small circle of 

 the gelatin is turned in the centre 

 of the slide, and then allowed to 

 dry. The objects are arranged on 

 the spot, and then, by carefully 

 breathing on the slide, they are 

 fiixed in position. If larger objects 

 are to be fixed to the slide a spot of 

 gelatin or gum that the object will 

 entirely cover is put on, and after 



drying, the object is fixed in the 

 same way. For larger and heavier 

 objects a circle of Brunswick black 



is turned, and after it has been 

 thoroughly hardened by heat, so 

 that when cool a needle point will 

 not mark it easily, the object is ar- 

 ranged on the spot and fastened by 

 warming again. 



In whatever way the object is 

 fastened, the next thing to be done 

 is to lay the slide on the plate and 

 heat it until it is perfectly dried 

 and ready to be covered. 



The slide is then centered on the 

 table and a circle of shellac, which 

 has been thickened and colored with 

 Chinese vermillion, is run around 

 the specimen, at such a distance 

 from it that its inner edge is just 

 larger than the cell to be used. The 

 cell is then laid on, centered, and 

 pressed hard to set it. If the slide 

 is slightly warm and the cement 

 thick, it will not run at all, but will 

 hold the cell firmly in place, so that 

 the cover can be put on at once. 

 If it is thin it must first be allowed 

 to harden somewhat. When ready, 

 as it will be in a few moments if 

 properly managed, a ring of the 

 same cement is run on the cell and 

 the cover is then laid on, pressed 

 down, clipped in position, and the 

 mount laid aside to harden. It is 

 well in an hour or so to remove the 

 clip and run cement in the joints 

 between cover-glass cell and slide, 

 in order to be certain that no air- 

 holes remain. It can then be re- 

 clipped, and set aside until the 

 cement is perfectly hard. The 

 mount is complete and will last a 

 long time if proper care is taken of 

 it. I think for security it is well 

 to put on additional rings of cement 

 more elastic than the shellac, and to 

 make a final finish for the sake of 

 appearance. I, therefore, put on a 

 ring of white zinc cement which 

 completely fills up the joints, and 

 makes a smooth surface from cover- 

 glass to slide. This must harden 

 several days, ^nd the slide is then 



