306 PRACTICAL MICROSCOPY. 



Objects for mounting in glycerine, such as a portion of 

 muscle with Trichinae in situ (Fig. 251), should be soaked 

 for some time in a mixture of equal parts of water, alcohol, 

 and glycerine, then exposed to the air under a bell-jar, or 

 in the desiccator ; the tissues gradu- 

 ally become filled with strong glycer- 

 ine, and the object is then ready for 

 mounting in that medium. 



Turning now to viscid media, 

 the author has made much use of 

 Farrant's medium, having mounted 

 mosses and starches very successfully 

 in it. It is a very convenient sub- 

 stance, seeing that it is used cold, 

 FIG. 251. 



and the slide cleaned with water 

 and a camel's-hair brush immediately after mounting ; 

 when on the following day the cover may be finished with 

 white zinc varnish and the usual coloured rings. 



The next description of mounting, that in glycerine jelly, 

 is one which, to a beginner, is frequently a stumbling-block. 

 It is an exceedingly convenient method to adopt when the 

 object would be rendered too transparent in balsam or 

 dammar, or when it is undesirable to dry it at all. 



In the preparation of the many things from the vegetable 

 kingdom, as mosses, algae, cuticles, and sections, and from 

 the animal kingdom, as many eyes and wings of insects, 

 gastric teeth, palates of the Mollusca, it is only necessary, 

 if they are sufficiently clean and not too dark in colour, to 

 put them for a few hours into a mixture of methylated 

 spirit, glycerine, and water (about equal parts of each), 

 although exactness is not necessary, as the mixture may 

 be varied to suit circumstances. 



When they are taken from this mixture, they must be 

 placed upon the centre of the slide, and the surplus fluid 



