212 PRACTICAL BOTANY 



or less below the point of insertion : these are the so-called 

 " stipules." The axillary bud will also be seen inserted in the 

 axil of the oldest leaf of the whorl. 



III. Remove and examine a whole bud under a low power : 

 either an apical or an axillary bud will do. It maybe necessary 

 to treat with acetic acid to remove the lime, which is often 

 present in considerable quantity : the bud may be subsequently 

 cleared with potash, and mounted in glycerine. The outer and 

 older leaves will show the characters above noted, but more 

 clearly, since they are younger, and their internodes shorter : 

 the structure of the cortex will thus be better understood in the 

 young than in the mature leaves. 



Examine also the cortex covering the short, young internodes 

 of the stern, and recognize the regular arrangement of the cells : 

 the cortex of each internode is composed of two series of lobes, 

 the one ascending from the lower node, the other descending 

 from the upper : these are in contact at the middle of the inter- 

 node, and elongate with it as it grows. Each lobe is composed 

 of nodes (3-celled), and unicellular internodes, which alternate 

 in a manner similar to that of the stem itself : compare this 

 arrangement with that of the mature cortex. 



Having thus examined the bud, remove the outermost whorls 

 of leaves with needles : then add a little potash and cover 

 the remaining central part of the bud with a cover-slip ; press 

 gently with a needle upon the cover-slip, watching the effect 

 under a low power. The outermost remaining leaves will be 

 pressed aside, and the apex of the stem will be exposed. 



Observe the terminal dome-shaped, apical cell, from which 

 segments are cut off by transverse walls. By comparison of the 

 terminal series of cells from several apices it may be concluded 

 that each segment cut off from the apical cell divides again 

 transversely into two, of which the lower cell without further 

 division develops directly into an internode, the upper divides to 

 form the numerous cells of the node from which are derived the 

 leaves, and the cortex. 



Compare this result with the appearance of the leaves when 

 young. 



Note that each cell contains a single nucleus. 



