282 PRACTICAL BOTANY 



same as that described for Lycopodium clavatum, the differences 

 depending chiefly upon the number of plates of xylem and 

 phloem, and variations in the manner and extent of the connection 

 between the plates of xylem. 



VI. Cut transverse sections of the leaf: this may 

 easily be done either by embedding the whole stem, 

 with the leaves attached, in paraffin, cutting transverse 

 sections of the whole, and then picking out the sections 

 of the leaves ; or by holding the stem with the leaves 

 between the finger and thumb, and cutting transverse 

 sections from the whole as from a solid mass. Mount 

 as before : examine under a low power and note 



1. The outline of the sections roughly triangular. 



2. The single layer of epidermis with cuticularized 

 outer wall : stomata are found on both the lower and 

 the upper surface. 



3. Beneath this is the mesophyll, with large in- 

 tercellular spaces : the cells, which form an irregular 

 network, are nearly globular, have thin walls, and 

 contain chlorophyll-corpuscles. 



4. At the centre is a single very small vascular 

 bundle. 



VII. Cut median longitudinal sections through the 

 bud : use material which has been preserved in alcohol, 

 or hardened in picric acid and then in alcohol. Mount 

 in glycerine, and examine with a low power : note that 

 at the lower part of the section the central vascular 

 cylinder will be easily recognized, while the bundles 

 from successive leaves pass obliquely through the cor- 

 tex, and insert themselves upon its margin. Passing 

 upwards, however, towards the apex, it gradually loses 

 its dark appearance (due to developed xylem); still 



