62 



BOTANY FOR BEGINNERS 



CHAP. 



large flat sections a cutting instrument with a flat side must be 

 used. The section when made may be so thin that light can 



FIG. 75. A transverse 

 section, cut through 

 A, Fig. 78. 



FIG. 80. A radial sec- 

 tion, cut through B, 

 Fig. 78. 



FIG. 



nge 



section, cut through 

 C, Fig. 78. 



pass through it, when it is said to be transparent. If the section 

 is thick and no light can pass through it, it is called opaque. 



EXPT. 50. Take a long kidney potato and cut sections from it; they 

 can be made in three directions, as fol- 

 lows 



(i) At right angles to its long axis ; this 

 will be a transverse section. 



(ii) Parallel to its long axis, and passing 

 through the centre ; this will be a radial 

 longitudinal section. 



(iii) Parallel to its long axis, but not 

 passing through the centre ; this will be a 

 tangential section. 



Mounting Specimens. After 

 the sections have been cut they must 

 be mounted on ordinary microscopic 

 slips. These are pieces of glass three 

 inches long by one wide. All fresh 

 specimens can be mounted in water 

 for examination by the microscope, but 

 for examination by a hand lens the dry 

 . object can often be used. Great care 



FIG. 82. Transverse section J 



through a square stem. must be taken to have both the micro- 

 scopic slip, and objects used in pre- 

 paring the specimens, perfectly clean, for the slightest 

 amount of dirt will spoil the section. In mounting the object 

 in fluid only a small drop of it should be used, just sufficient 



