HOW TO USE THE MICROSCOPE 33 
together with the sections at the bottom of the cup, to a wide- 
mouth bottle, and covered with alcohol, glycerine, and water 
mixture; or if it is desired to stain the specimens, they should 
be placed in a weak alcoholic solution. 
Specimens having a hard, woody texture should be cut on 
a sliding microtome by means of a special wood knife, which 
is especially tempered to cut woody substances. Woody roots, 
wood, or thick bark may be cut readily on this microtome when 
they have been embedded by the quick paraffin process. The 
knife in the sliding microtome is placed in a horizontal position, 
slanting so that the knife-edge is drawn gradually across the 
specimen. After cutting, the sections are treated as described 
above. 
The thickness of the sections is regulated by mechanical 
means. After a section has been cut, the block containing the 
specimen is raised by turning a thumb-screw. In this microtome 
the knife, as in the rotary type, is fixed, and the block contain- 
ing the specimen is movable. 
If the specimen has been infiltrated with, and embedded in, 
paraffin or collodion, the treatment of the sections after cutting 
should be different. 
In the case of paraffin, the sections are fastened directly to 
the slide, and the paraffin is dissolved by either chloroform or 
xylol. The specimen is then placed in 100, 95, and 45 per cent 
alcohol, and then washed in water. These sections are now 
stained with water-stains, brought back through alcohol, cleared, 
and mounted in Canada balsam. 
If alcoholic stains are used, it will not be necessary to de- 
hydrate before staining, and the dehydration after staining will 
also be eliminated. 
Sections infiltrated with collodion are either stained directly 
without removing the collodion or after removal. 
FORMS OF MICROTOMES 
The hand cylinder microtome (Fig. 34) consists of a cylindrical 
body. The clamp for holding the specimen is near the top 
below the cutting surface. At the lower end is attached a microm- 
eter screw with a divided milled head. When moved forward 
one division, the specimen is raised o.or mm. ‘This micrometer 
