i6 



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. 



FIG. 7. Showing the 

 planes in which sections 

 are cut, A, transversely; 



B. longitudinal radially; 



C, longitudinal tangen- 

 tially. (After Stevens.) 



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. 



