HOW TO PREPARE AND EXAMINE SECTIONS 67 



These are the places where the leaves were inserted ; they are called 

 leaf scars (Fig. 89, D). 



EXPT. 59. Cut a transverse section of a twig of the Lime tree. 

 Note that the wood is made up of a number of rings. Each 

 ring is made up of (a) a dark coloured layer and (b) a light coloured 

 layer. These are shown in Fig. 90. Each ring represents the amount 

 of growth which has taken place in one year. The age of the tree can 

 be told by the number of rings of wood present 



FIG. 



3. Skeleton leaf of Holly. 

 (Half nat. size.) 



FIG. 89. A piece of Cabbage stalk. 

 A= epidermis ; B = cortex ; C = vas- 

 cular tissue ; D = leaf scar. 



EXPT. 60. Cut in autumn a longitudinal section of the stem of the 

 Horse-Chestnut so as to pass through the base of a leaf. Examine such 

 a section with a hand-lens. Note 



(i) The base of the leaf which is connected with the stem (see A, 

 Fig. 91). 



(ii) A layer of cork which consists of cells ; the layer passes right across 

 (see B, Fig. 91) the base of the leaf. This layer, when the leaf has 

 performed all its work, separates the leaf from the stem and covers up 

 the scar which is left. 



EXPT. 61. Cut a transverse section of the stem of the Maize, 

 and mount it in glycerine. If the stem has been preserved in alcohol 

 so much the better, because there will be a smaller number of air bubbles 

 present, and the section will be far clearer. Examine with the low 

 power of the hand-lens. Note 



(i) The primary cortex. This surrounds the vascular bundles and 

 helps to support the plant in an erect position. 



V 2 



