PRACTICAL BOTANY. 



open, dehiscence having taken place in a plane 

 parallel to that of the leaf. 



II. Cut out as thick a piece of the stem as can be 

 found, and about one inch in length : note on the surface 

 of transverse section a central white dot ; this is the 

 single central vascular bundle. Slice off the upper 

 surface of the stem with a razor till the whole course 

 of the vascular bundle is laid bare, and observe with 

 a lens 



1. The course of the central vascular bundle, which 

 is directly longitudinal and median. 



2. The smaller lateral bundles, which pass from the 

 central bundle without branching, into the leaves, and 

 traverse the midribs of the leaves. 



III. Cut transverse sections of a well developed stem : 

 mount some in glycerine, others in Schulze's solution 

 (others again may be mounted in acid solution of 

 aniline sulphate). Examine first under a low power, 

 using a high power when necessary, and observe the 

 following tissues in succession, starting from the 

 periphery of the section : 



1. At the periphery a layer of small, thick-walled 

 cells, forming an ill-defined Epidermis, with no 

 stomata; it is covered externally by a continuous 

 Cuticle. Beneath the epidermis, and not clearly 

 marked off from it, is 



2. The Cortical tissue : the cells- of the peripheral 

 part of it have thick, stratified, and lignified walls, with 

 no intercellular spaces. Passing inwards there is seen 

 a gradual decrease in thickness of the walls, and 

 increase in size of the cells, till an abrupt limit is 

 reached at 



