Appendix IT 
HISTOLOGICAL TECHN IQUE 
In this chapter the various methods which are commonly 
employed in the preparation of plant materials for microscopic 
examination and the reagents used in the examination of the 
same will be discussed. 
Makinc oF SECTIONS 
FREE-HAND SEcTIONING.—Free-hand sections are usually 
Satisfactory for the general examination of roots, stems, leaves, 
barks and many fruits and seeds. Material which is fresh may 
be sectioned at once, but dry material should be well soaked in 
warm water before using. Fresh material should always be 
kept moistened in water on account of the danger of cell shrink- 
age through loss of water. Dried membranous or subleathery 
leaves should be kept in a moist chamber for at least 24 hours or 
until sufficiently supple before they are sectioned. Dried 
woody roots and stems can usually be best prepared for section- 
ing by soaking segments of these in equal parts of alcohol, 
glycerin and water for several weeks prior to using. Very hard 
material like heartwoods, the shells of nuts and seeds, may 
be softened in solution of caustic potash or ammonia water and 
then washed free of alkali before sectioning. Fine shavings can 
then be whittled off of these with a sharp knife. In some cases 
alternatingly boiling and cooling the material will suffice. 
The object to be sectioned is held between the thumb and 
finger of the left hand. If tender and flexible, such as a fresh 
leaf, it must be placed between the two flat surfaces of elder pith 
before sectioning. A segment of pith about an inch long is 
halved lengthwise with a sharp knife and a portion of the leaf is 
held between the halves of pith while the section is cut through 
pith and leaf. The pith is later separated from the leaf section. 
Sections through other delicate parts of plants, as buds, slender 
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