MAKING PERMANENT MOUNTS 



269 



haematoxylin for about ten minutes, rinse them thoroughly in 

 water and then in 35 per cent, alcohol and again in 50 per cent, 

 alcohol; pass them quickly through acid alcohol (one drop 

 hydrochloric acid in 50 c.c. of 70 per cent, alcohol), and then 

 put them through 70, 85, and 95 per cent, alcohols, leaving them 

 about two minutes in each grade. Now clear the sections for 

 about two minutes in the mixture of equal parts of bergamot 

 oil, cedar oil, and carbolic acid, and mount them in Canada 

 balsam. Here, as in all staining, the time ratios for the different 

 reagents will need to be determined for different materials. 



Making Permanent Mounts in Glycerine or Glycerine 

 Jelly. Filamentous algae and fungi are pretty certain to shrink 

 and become plasmolyzed when put through the process of mount- 



FIG. 146. Turn table for cementing coverglasses to slides. For use where the mounting 



medium is glycerine or glycerine jelly. 



ing in balsam, but this danger can be easily avoided by mounting 

 them in glycerine or glycerine jelly, preferably the latter. Fix 

 the subjects in the chrom-acetic fixative described on page 260; 

 wash' them in running water for a few hours and place them 

 in a 0.5 per cent, aqueous solution of eosin for several hours; 

 place for five minutes in a one per cent, solution of acetic acid 

 in distilled water; wash out the acid completely in water and 

 transfer the material to a ten per cent, solution of glycerine; 



