PREPARATION AND MOUNTING 77 



or table. The material to be cut is fixed in the 

 tube either by suitable wedges or by being embedded 

 in wax. The screw is used to raise the material 

 above the table, so that by drawing the razor 

 resting on it through the object a thin section is 

 made. The first cut, or the second, will level the 

 object, then a slight turn of the screw will raise it 

 sufficiently for the cutting of a suitable section. 

 Before each cut the razor should be well wetted with 

 dilute methylated spirit, and it should be kept very 

 sharp. Paraffin wax is generally used for embedding. 

 It must be melted by placing it in a suitable jar 

 and holding it in boiling water, taking care that no 

 water gets into the jar. The stem to be cut is first 

 dipped into the melted wax, so as to be thinly coated 

 with it ; then it is held in position in the microtome 

 tube while sufficient wax is run in about it. As the 

 wax shrinks on cooMng, plenty should be used. 



Very woody stems need to be softened by long 

 soaking in water before satisfactory sections can be 

 made of them, and if they are resinous they should 

 also be treated with alcohol, which will dissolve 

 out the resins. In some cases woody stems require 

 to be boiled in water for a lengthy period. Indeed, 

 most stems to be sectioned are improved by a day 

 or two in methylated spirit for removal of resins, 

 and afterwards a few days in water to remove 

 gums. 



It is usual to stain vegetable sections, not merely 

 to give them an attractive appearance, but to render 

 details of structure distinct. 



f Prior to staining, the sections may need to be 

 thoroughly bleached. Bleaching fluid is made by 



