38 PRACTICAL HISTOLOGY [V 



remove all excess of 95 p.c. alcohol before it is placed 

 in the clove oil. 



In removing a section on a lifter from alcohol to 

 clove oil, take care to remove all excess of alcohol. 



The complete dehydration of the sections is rendered more 

 certain by placing them in absolute alcohol after 95 p.c., but 

 absolute alcohol is expensive and is not necessary, since clove oil 

 will take up a small quantity of water. When xylol instead of 

 clove oil is used as the clearing agent, greater care must be taken 

 to dehydrate the specimen. 



When the sections are transparent, tilt the slide 

 slowly and let the clove oil run off, keeping the sections 

 in place with the aid of a needle. Let the slide stand 

 vertically on a piece of blotting-paper for a minute or 

 two to drain: with the clean-cut edge of a piece of 

 blotting-paper remove the clove oil around the specimen. 

 Clean a cover-slip by rubbing it on a smooth, hard 

 surface, with a piece of clean silk or linen. Let a small 

 drop of fluid Canada balsam 1 dissolved in xylol fall on 

 the section. With the aid of a needle gently lower the 

 cover-slip on the balsam. 



The specimen may be placed on a warm bath for about half- 

 an-hour, the cover-slip then presses out the excess of balsam, and 

 the balsam at the edges sooner becomes firm. Injected specimens, 

 and those containing fat globules stained with osmic acid, should 

 not be warmed. 



3. Place a section for half-an-hour in each of the following 

 fluids, hsematoxylin (whichever was not used in 1), alum carmine, 

 carmalum. Mount them and compare the staining. 



4. Staining with methylene blue or with saffranin. With 

 these and a number of other reagents it is generally best to 



1 If the balsam is thick, pour a little xylol into the bottle. 



