32 



MICROSCOPICAL RESEARCH 



this not only hardens the sections, but also frees them from the clearing 

 oil, which, if not removed before the sections are permanently 

 mounted, diffuses out afterwards and discolours the balsam; a common 

 cause of the dirty brown appearance of so many commercial slides. 

 The sections may remain in the benzol balsam indefinitely, if needs be, 

 without deterioration in colour, as in this condition they are practically 

 mounted. In my own work I have sometimes a dozen of these 

 "balsam-pots," each containing half a gross of sections waiting for days 



A. B. 



Fig. i8. — Complete staining and slide-mounting outfit. A. Storing cabinet. 

 B. Microscope, mounting blocks, section dish, drying tray, &c. 



and in some cases weeks before they are permanently mounted, the 

 rims are smeared with balsam and a glass cover placed on them, which 

 practically seals them protecting the sections from dust, and the 

 benzol from evaporation. The sections are mounted permanently by 

 placing a drop of ordinary Benzol balsam on the centre of a plain slip, the 

 section is lifted out of the thin benzol-balsam and placed in this; and 

 then a cover slip is placed on the section, the whole being clamped in 



