252 PREPARATION OF SECTIONS 



of the stem usually suffices, provided it extends from the sur- 

 face to the pith. Tender, flexible parts, such as the blades of 

 leaves, will need to be inclosed in elder pith before sectioning, 

 and a good stock of pith should be kept on hand for this pur- 

 pose. A piece of pith about an inch long is laid on the table 

 and while held firmly between the thumb and. fingers to keep 

 it from cracking it is halved longitudinally with a sharp knife. 

 If a leaf section is desired a strip of the leaf is held between' 

 the halves of pith while the section is cut through pith and 

 all. Sections of delicate stems and roots and of buds and 

 flowers may be made in the same way, only a groove should 

 be made in the pith, of a size to hold the parts firmly enough 

 while not crushing them. It is surprising how much really 

 good work can be done with simple appliances of this sort. 



To get sections of the stone-cell tissue of nuts saw off as thin 

 slices as possible with a hack saw and rub these down to the 

 requisite thinness between two water hones kept wet. This 

 is a slow process but it yields fine sections. A simpler way 

 is to whittle off fine shavings with a very sharp knife. These 

 shavings roll up and must be forcibly straightened out. They will 

 break when this is done but the small bits will do. (See p. 310.) 



A sharp razor is a necessity to successful section cutting; 

 and it is not sharp enough until it will clip a hair held so it is 

 free to bend before the razor. A razor half hollow-ground 

 on both sides Is a good one for this purpose. The dealers 

 offer razors ground flat on one side, but it is impossible to keep 

 them sharp by the usual methods. A good shaving razor, 

 so only the blade is not ground too thin, makes a suitable sec- 

 tion razor. 



While cutting sections keep the razor blade wet with about 

 60 per cent, alcohol, and slide the sections into a dish of water 

 before they have time to become dry. Never let sections be- 

 come dry at any time, else they will shrivel and their cells will 

 become filled with air which will prove a nuisance under the 

 microscope. 



In studying stem and root structure three sections, each 



