112 PKACTICAL BOTANY. 



or of a foliage branch of an old plant : treat with strong 

 potash [or better, with dilute potash for twenty-four 

 hours] : examine with a low power, and observe, if the 

 section be median 



1. The Apical cone (punctum vegetationis). 



2. Leaves, in successive stages of development, 

 seated laterally. 



3. In the older leaves, Vascular bundles, which 

 enter the stem. 



On following the course of these vascular bundles it 

 will be seen that on entering the stem they proceed at 

 first towards the centre : before reaching it they curve 

 downwards, and finally turning again outwards they 

 approach the periphery of the stem. We thus see that 

 in young stems of Maize the course of the bundles cor- 

 responds to the Palm-type, though as the stem grows 

 older, and the internodes develop, the correspondence 

 is less obvious, by reason (1) of the almost straight 

 course pursued by the bundles in the internode, and 

 (2) the complications which arise at the node. 



STEM. ARBOREOUS TYPE. 



I. Examine preparations of the old stem of Yucca 

 or Dracaena, in which the thin-walled parenchyma 

 has been allowed to rot away, while the vascular 

 bundles remain. On comparing transverse and longi- 

 tudinal sections of such stems, it may be seen, with the 

 naked eye 



1. That the central Primary bundles are isolated, 

 and that the course of each bundle may be traced as 

 starting from below at the periphery of the stem, then 



