Mounting Before Siaining 77 



covered for some time it is probable that the alcoholic content has been 

 reduced by evaporation. Never, at any time during the transferring of 

 sections, allow them to become dry. They may be carried directly from 

 the 70% alcohol to the stain if it is an alcoholic one, or first into water, 

 then into stain, if it is aqueous. (Remember to remove luidesirable pig- 

 ments or crystals before staining.) 



When ready for dehydration, transfer through 50%, 70% and into 

 95% alcohol. Then clear the sections by either of the following meth- 

 ods. 



Method 1. Transfer sections into carbol-xylol (page 410), 2-3 min- 

 tites. Keep carbol-xylol covered at all times to prevent evaporation of 

 xylene. Dip the edge of a slide into the carbol-xylol dish and slip the 

 section in place with a needle or forceps. Drain thoroughly and flush 

 off excess carbol-xylol with toluene or xylene, 2 or ?> times. Add several 

 drops of motuitant and cover glass. Press cover firmly in place. Several 

 hours later, after the resin has thickened, press down again. If the cover 

 glass insists on tilting or lifting, place a small ^veight on it or clamp it 

 with a clothes pin overnight. Bertram {1958) describes a weight ^vhich 

 will not stick to the mountant and cover glass. 



Method 2. Transfer the sections to absolute alcohol containing 5% 

 of chloroform to prevent the alcohol from dissolving the nitrocellulose. 

 Clear with benzene and moimt as above, omitting the carbol-xylol. 



Do not attempt to dissolve or remove the nitrocellulose from sections; 

 they will become too difficult to manipulate. When using carbol-xylol, 

 keep fingers out of the solution. Wash off any that does get on the fingers 

 and rub lanolin on the skin. 



A method for transferring sections to slides, particularly thin sections, 

 is as follows: slip a piece of cigarette paper imder a section and spread 

 it smoothly on the paper with a brush or needle. Place the paper plus 

 the section on a slide with the section between the slide and paper. Blot 

 firmly with a piece of filter paper. Peel off the cigarette paper and rinse 

 the section with toluene or xylene. Add moimtant and cover glass. 



Mounting Before Staining 



Sections are affixed to slides for staining in this method. 



Method 1 



a. Albumenize slide. 



h. Press section on with filter paper. 



