16 PHARMACEUTICAL BOTANY 
KINDS OF SECTIONS 
1. A transverse or cross-section is one made horizontally through 
the object, hence its plane lies at right angles to the long axis. 
2. A radial-longitudinal section is one which is made parallel to 
the long axis of the object in such a way 
that it lies in plane of the radius. 
3. A tangential-longitudinal section is one 
made parallel to a plane tangent to the 
cylinder. This type of section is therefore 
prepared by cutting parallel to the outer 
long surface. 
MICROTOMES 
Microtomes are instruments employed to 
facilitate the cutting of sections of organic 
tissues. The three most commonly used 
types are the hand, sliding and rotary 
microtomes. 
Hand Microtome. —This type is shown in 
Fig. 8. If the object is sufficiently hard to 
bear the strain, it is placed directly in a 
clamp at the upper end of the tube that is 
tightened by the screw seen on the side of 
the tube, or it may first be inclosed in elder 
pith or cork and then clamped in. The 
object to be sectioned is raised a little at a 
time through the hole in the glass plate at 
the *top by turning the finely graduated feed 
near the base of the tube. The section razor 
is then laid flat on the glass plate and pulled 
across the object with a long sliding motion. 
The upper surface of the razor blade is kept wet with 50 per cent, 
alcohol and after several sections have been cut they can be swept 
by the finger or camels hair pencil to a dish of water. Each 
division of the feed represents 10 microns, so that the thickness of 
sections desired can be regulated by moving the feed, accordingly, 
just before each stroke of the razor. 
Fig. 7.—Showing the 
planes in which sections 
are cut, A, transversely; 
B. longitudinal radially; 
C, longitudinal tangen¬ 
tially.. ( After Stevens.) 
