CUTTING SECTIONS 



planes, parallel to the plane of the paper in Fig. I. The line 

 including the central points of successive imaginary transverse 

 sections is the organic axis. 



Radial and tangential sections are both in planes vertical to 

 that of the paper in Fig. I : a radial section (A E B) includes the 

 organic axis (E), and a slice of tissue thus cut when examined 

 from a direction indicated by either of the arrows (r) will show 

 in surface view those cell-walls which run radially : a tangential 

 section (c D) does not include the organic axis (E), and such 

 sections when examined from a direction indicated by the 

 arrows (y y) will show the tangential walls in surface view, 

 while the radial walls, previously seen in surface view, would 

 present their cut edges to the observer. 



In the case of tangential sections only the central part of the 

 section (i.e. the part near to y y) is to be examined, for ob- 

 viously in the more lateral parts of the section (c D) the radial 

 lines are not cut vertically but obliquely. 



In all cases the sections must be cut accurately in the plane 

 intended : if the sections be cut obliquely the difficulty of 

 understanding the structure will in almost every case be 

 enormously increased. 



A razor of good quality is the best cutting instrument : there 

 is some variety of opinion as to the best form of blade ; some 

 prefer a hollow-ground razor, which, though well suited for 

 cutting small sections, will not serve for sections of large area ; 

 for such work a razor with one flat side is recommended. For 

 general use, not only in cutting small objects and soft tissues, 

 but for the every-day work of the laboratory, an ordinary, very 

 slightly hollow-ground razor of good quality will be found the 

 most useful. The razor should be stropped to a smooth edge, 

 and the blade should be carefully protected when not in use : 

 it should never be left open on the work-table, and the blade 

 should always be cleaned after use, since the acid juices of 

 plants are apt to corrode it. It will be found convenient to 

 have a glass of water (or weak spirit when resinous tissues are 

 being cut) on the work-table, into which the blade of the razor 

 may be plunged at once after use ; this will prevent immediate 

 corrosion. 



