64 MOUNTING AND PREPARATION OF OBJECTS. 



etc., may be mounted in glycerine and a thick solu- 

 tion of gum in camphor water. Opaque objects as 

 sori of ferns, may after soaking in turpentine be 

 mounted in balsam ; but others require a process of 

 maceration, staining and dissection, which will be 

 best understood by a reference to some text-book on 

 botany. 



Pathological and histological objects are prepared 

 and mounted by the following methods. 



When the intimate structure of tissue requires in- 

 vestigation, it should be obtained as fresh as possible 

 and a small portion immediately teased out with 

 needles, in a little serum or glycerine on a glass 

 slide. It will be found advantageous to insert the 

 needles into light wooden handles with a pliers, and 

 to place a piece of black cloth or white paper under- 

 neath the slide during dissection. When the dissec- 

 tion is finished, the tissue is steeped for three 

 minutes in a half per cent, solution of chloride of 

 gold, or a small quantity of the toning solution used 

 for prints diluted with three or four times its weight 

 of distilled water. After an immersion of three 

 minutes it is removed from the gold solution and 

 exposed to the light in a little glycerine, until it 

 assumes a violet gray shade. This will take about 

 twelve hours. A half per cent, solution of nitrate of 

 silver may be used in the same way, and is extreme- 

 ly useful for histological work especially the demon- 

 stration of the endothelial linings of serous mem- 

 branes. 



These preparations are finally mounted in gly- 



