METHODS OF MOUNTING. 429 



2. Carbol-xylol. 



Carbolic acid crystals (melted), 1 vol. 



Xylol, 3 vols. 



This mixture is much more tolerant of water than pure xylol. 

 Sections dehydrated in 95 per cent, alcohol may be cleared with 

 this reagent, which does not dissolve collodion. The carbolic acid 

 used should be pure, but need not be the more expensive synthetic 

 product. 



3. Oil of Bergamot. This light-green essential oil clears well and 

 does not dissolve collodion. It may be used when 95 per cent, 

 alcohol has been employed for dehydrating. 



4. Oil of Origanum. The oleum origani cretici should be used. 

 It is of light-brown color and clears sections dehydrated in 95 per 

 cent, alcohol or stronger. It slowly discharges anilin-colors. 



5. Oil of Cloves. This clearing-agent dissolves collodion and 

 discharges anilin-colors. It may be used when it is desired to get 

 rid of the collodion used for embedding after the sections have been 

 stained. This removal is favored by dehydration in absolute alcohol 

 before clearing. 



6. Oil of Cedar- wood. This, when pure, has a very light-yellow 

 color and smells like cedar-wood. It should be free from the more 

 pungent odor of the oil derived from the leaves. This essential 

 oil does not discharge anilin-colors, and is, therefore, useful when 

 those dyes have been employed. It clears slowly, but well, and 

 may be used after dehydration with 95 per cent, alcohol. 



Methods of Mounting. 



Sections that have been treated by the foregoing methods of 

 preparation are fitted for mounting in a solution of some resin. 

 The most commonly employed are Canada balsam and dammar. 

 The best solvent for these resins is xylol, though chloroform and 

 benzol are sometimes used for this purpose. All traces of turpen- 

 tine should be removed from the balsam before its solution, to avoid 

 the discharge of stains with hsematoxylin or anilin-dyes which tur- 

 pentine occasions. 



When sections are transferred from alcohol to a clearing-agent 

 they float upon the surface of the latter, and can then be flattened 

 and all folds removed. As the alcohol is extracted the sections 



