330 PRACTICAL BOTANY 



The bundle-system may be actually demonstrated by dissection 

 in the stem of one of the larger forms, viz. E. Telmateia. Take 

 a fresh and well-grown shoot, and cut from the thickest part of 

 it a piece about four inches in length, and including a node ; then 

 remove from it the outer tissues, and scrape the soft parenchyma 

 away till the vascular bundles are laid bare ; then slit tha hollow 

 stem longitudinally, flatten it out, and carefully scrape away the 

 softer tissues from the inside till the vascular bundles are clearly 

 seen ; then treat for some hours with alcohol to remove the 

 air-bubbles from the intercellular spaces, and warm gently in 

 weak solution of potash : the preparation may be preserved 

 in glycerine, or alcohol. If such a preparation be care- 

 fully made, it will show] the course of the* vascular bundles 

 in the internode, as well as the branchings and fusions at 

 the node. 



Returning to the study of the details of the transverse 

 sections of the internode, examine them under a high 

 power, and observe 



1. The superficial cells of irregular size and shape 

 which form an ill-defined epidermis, many projecting as 

 rounded excrescences beyond the general surface : their 

 walls are thick, and show on the outer surface small 

 and irregular projections : the cell-contents are scanty. 

 Note that on the sloping sides of the ridges, and im- 

 mediately above the chlorophyll-parenchyma, stomata 

 may be seen cut in section, and showing two guard- 

 cells which surround the pore, and two subsidiary 

 cells which fit closely round them : there is a large 

 respiratory cavity beneath each stoma. 



2. The subjacent cells, composing with the epider- 

 mis the band of thick- walled tissue before mentioned, 

 have cellulose walls (blue with chlor-zinc-iodine), with 

 narrow pits. 



3. The cells of the chlorophyll-parenchyma are 



