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 containing 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 dehydrate 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 micrometer screw with a divided milled head. When moved forward one division, the specimen is raised 0.01 mm. This micrometer screw has an upward movement of 10 mm. The cutting surface consists of a cylindrical glass ring.
Fig. 34.—Hand Cylinder Microtome
