TOOLS AND METHODS OF WORK 



21 



The section-knife best suiteci for general use in botanical work is 

 one having a straight handle with a fixed stout blade three to three and 

 a half inches long, and slightly hollow-ground on both sides ; the knife 

 may be set on any ordinary stone, with the use of water and fine emery 

 or carborundrum powder. A very small amount of this powder is 

 placed on the stone with a few drops of water, and first rubbed into a 

 very fine paste with an old disused section-knife. The knife for use 

 is now set on this by passing it lightly over the stone edge forward, the 

 traverse being from apex to base, and base to apex. The back and 

 edge of the knife must be parallel to each other, and in true line from 

 back to edge. 



The Art of Cutting Sections. 



To make a complete study of a solid mass of tissue, sections must 

 be cut at different planes to each other, viz., "transverse," "radial- 

 longitudinally," and "tangential-longitudinally." The transverse section 



Fig, 13. — ^Diagram of dicotyledonous stem. i. Tangenital area passing through the bast 

 fibres. 2. Tangenital area, passing through the xylem. 3. Radial line, 

 passing through the pith. 



