100 THE MICROSCOPE 



razor. By thus turning the screw beneath very slightly, sections 

 of any degree of thickness can be obtained. 



The cellular tissues of plants (certain leaves, flowers, and 

 fruits) are softened, and at length destroyed by weak nitric or 

 hydrochloric acid (i part acid to from 20 to 50 of water), while 

 the fibrous and vascular textures remain behind, constituting the 

 skeleton of the leaf, flower, calyx, or fruit. Almost all vegetable 

 tissues are more easily investigated when they have been preserved 

 for some time in viscid media, which are admixable in all propor- 

 tions with water. Leaves and stems, when well saturated with 

 syrup or glycerine, are easily dissected into their component 

 tissues. They must first be placed in very dilute solutions, which 

 may be concentrated by very gradual evaporation, or the strength 

 of the solution may be increased by the addition of small quanti- 

 ties of strong syrup or glycerine from day to day. The beginner 

 is advised to examine various specimens of jams and preserved 

 fruits, as they, having been long soaked in syrup, have become 

 exceedingly transparent, and are admirably fitted for microscopic 

 demonstration. The spiral vessels, woody and cellular tissues, can 

 be obtained without any trouble, and the minute structure of the 

 different vegetable tissues may be most clearly demonstrated. 



Pollen Grains are among the most interesting objects. They 

 can easily be obtained by shaking the anther of any fully-expanded 

 flower upon a glass slide, and may be mounted dry in aqueous 

 fluids, or in Canada Balsam and Benzole. The external markings 

 of seeds of plants are deserving of attentive examination. They 

 may be examined as dry objects without any preparation whatever, 

 by reflected light. 



Seaweeds, to be preserved permanently, should be allowed to 

 soak for some time in pure water. Small pieces may then be 

 removed and transferred to glycerine. 



Some of the most beautiful vegetable sections which we have 

 seen have been mounted in glycerine. The mixture of gelatine 

 and glycerine, or gum and glycerine, will also be found good media 

 for mounting many vegetable structures ; chloride of calcium 

 forms a useful preservative fluid in many instances. Creosote 



