702 Botanical Microtechnique 



Temporary and Semipermanent Slides 



The torcgoino outline of methods of preserving ijulk materials 

 leads to a consideration of methods of preparing mounts for micro- 

 scopic study. The simplest method ob\iously consists of mounting 

 a small quantity of the material in a drop of water. However, water 

 mounts dry out during prolonged study, and it is better to mount 

 the material in 10% glycerin. As the water evaporates, introduce 

 more glycerin solution under the cover glass at intervals, until no 

 further evaporation takes place. Such preparations can be kept almost 

 indefinitely if stored flat and handled with care. 



The preservative and swelling action of lactic acid and phenol 

 (carbolic acid) is utilized in an important class of formulas. More 

 or less durable slides of algae, fungi, fern prothalli, sections, and other 

 small objects can be made by mounting in one of these lactophenol 

 solutions, with or without added dye. The following selected formulas 

 are taken from Maneval's valuable compilation of these methods. 



Aman's Lactophenol 



Phenol (melted) 20 cc. 



Lactic acid 20 cc. 



Glycerin 40 cc. 



Water 20 cc. 



Phenol-Glycerin 



Phenol (melted) 20 cc. 



Glycerin 40 cc. 



Water 40 cc. 



If a staining effect is desired, add a \% aqueous solution of either 

 cotton blue, aniline blue, or acid fuchsin as follows: 



Lactophenol 1 00 cc. 



Glacial acetic acid to 20 cc. 



Dye solution 1 to 5 cc. 



The optinuun concentration of glacial acetic acid is that which 

 produces no (()llaj)se oi bursting of cells or filaments. Try the above 

 formida and dilute wiih lactophenol uinil tlie best ])roportions are 

 established. 



Glycerin-jelly preparations are a finther advance toward perma- 

 nent slides and are preferretl to glyceiin mounts if the slides must 

 withstand considerable use. The moinuing mediiun is made as follows: 



Gelatin 5 g. 



Water 80 cc. 



Glycerin 85 cc. 



Phenol (dissolved in 10 drops water) 5 g. 



