147 



0.5 /i or less. The stains are dissolved in cnvettes filled with water (ap- 

 proximately a knife's point to a cuvette). Staining is effected in about 4-5 

 hours. Bismarck brown, malachite green, and other stains have been 

 tried, but with less satisfactory results. Staining greatly facilitates the 

 localizing of the sections as unstained sections thinner then 0.3 /^ are often 

 difficult to locate under an ordinary microscope. 



After staining, the slide is rinsed with water and allowed to dry. Mean- 

 while, minute glycerine jelly cubes (about 1 mm^) are cut, and a number of 

 cover-slips carefully cleaned. The cubes are placed on those parts of the 

 shde which have previously been marked with the diamond. The size of 

 the cubes should vary in relation to the size of the section-bearing areas. 

 A cover-shp is then placed on top of each jelly cube, and the jelly slowly 

 melted. Care should be taken to prevent the jelly from spreading to the 

 edge of the cover-slip. 



The slide is then sealed with paraffin-wax. To this end a small piece of 

 paraffin (melting point about 70 centigrades) is placed at the edge of the 

 cover-shp. The shde is then slowly heated in order to melt the paraffin 

 which is sucked in under the cover-slip forming a protecting zone around 

 the section-bearing glycerine jelly (Fig. 265). When the paraffin has 

 cooled and hardened, the shde is cleaned with a knife and cotton wool 

 soaked in benzol. 



For further information see "Sjostrand Ultra-Microtome. Instructions 

 for use". (Distributed by LKB-Produkter, Stockholm 12.) 



