Laboratory Equipment. 



377 



material should be well soaked in warm water before using. It is still 

 better, after soaking dry roots, stems, or pieces of dry wood, to place 

 them in equal parts of alcohol, glycerine, and water, for a week or so 

 before sectioning. 



To cut a cross section of a stem or root, trim one end squarely across 

 with a sliding stroke of a sharp knive ; then hold the object between 

 the thumb and forefinger, flood the upper face of the razor with water 

 or 50 % alcohol, and rest it on the forefinger with the point against the 

 object ; regulate the thickness of the section to be cut by raising or 

 lowering the forefinger, and cut the section with a long forward stroke 

 (see Fig. 200) . The sections usually need to be made as thin as they 

 can possibly be cut. The upper face of the razor is kept wet in order 



Showing the method of holding the object and razor in cutting sections 

 free-hand. 



that the sections may easily slide over the blade without crumpling or 

 rolling up. As the sections are cut, they should be transferred to a dish 

 of water, and should not at any time be allowed to dry. 



Leaves and some succulent stems and roots need to be embedded in 

 elder pith before sectioning, and for such purpose a 

 good supply of dry pith should be kept on hand. A 

 piece of the pith not more than an inch in length is 

 halved longitudinally with a sliding stroke of a 

 knife, while held on a table firmly between the thumb 

 and fingers to keep it from breaking. If a leaf is to 

 be sectioned, a strip of it is placed between the pieces 

 of pith, and then leaf and pith are sectioned to- 

 gether, the razor being kept wet as before, preferably Method of inclos- 

 with 50% alcohol. If succulent stems and roots are ing an object in 

 to be sectioned, longitudinal V-shaped grooves are cut 

 in both pieces of pith, of proper size to clamp the material firmly 

 (Fig. 201). 



FIG. 201. 



