182 PRACTICAL BOTANY. 



VI. Cut transverse sections of the leaf; this 

 may easily be done either by embedding the whole 

 stem with the leaves attached in paraffin or cocoa- 

 butter, cutting transverse section 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 circularised 

 outer wall : Stomata are found both on 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 granules. 



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 re- 

 cognised, while the bundles from successive leaves pass 

 obliquely through the cortex, and insert themselves 

 upon its margin. Passing upwards, however, towards 

 the apex, it gradually loses its dark appearance (due to 

 developed xylem ) ; still its continuity may be traced 

 up to the apical cone, as a bright-looking strand of 

 formative tissue consisting chiefly of prosenchymatous 



