138 METHODS OF MICROSCOPICAL RESEARCH. 



days, and at length the excess of the medium can be 

 washed off with a soft brush, the slide, as in the 

 case of the glycerine jelly, be allowed to dry, ringed 

 with shellac varnish, and finished with white zinc or 

 asphalt. 



Specimens to be mounted in aqueous media, such 

 as carbolised water, camphor water, glycerine and 

 water, &c., should be immersed for some hours in 

 distilled water, and mounted, from that, in a shallow 

 cell as already described in the case of glycerine. 



The Preparation and Mounting of Insects. 



There are several processes for preparing and 

 mounting insects, each of which possesses special 

 advantages, in respect of the results and appear- 

 ances it may be desired to obtain. Whenever it is 

 possible, and except for special purposes and in 

 dissections, insects should be mounted " without 

 pressure," since the flattening them out under 

 pressure results in distortions, displacement of the 

 parts and organs, and unnatural, and therefore false 

 appearances. It is, however, impossible to mount 

 all insects, or their parts, without pressure, and the 

 following process will give good results : 



Place the insect in pure liq. potass, mixed with i 

 ammonia fort. The insect must not be allowed to 

 remain too long in this solution, and must be tested 

 from time to time by placing it in water and press- 

 ing the thorax. When the thorax is soft and the 

 legs flaccid, immerse the insect in water for from 

 fifteen to twenty-four hours, then soak it in glacial 

 acetic acid and glycerine (half and half) for some 



