CHARACE.E 413 



these are in contact at the middle of the internode, 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. 



A more exact and satisfactory method is to cut longitudinal 

 sections through the bud : this may be done roughly from fresh 

 material, by holding the bud between the finger and thumb, and 

 slicing it longitudinally with a razor : the sections thus cut are to 

 be mounted in water; or the apical buds may be hardened in alcohol, 

 and embedded in paraffin : sections are then to be cut longitudin- 

 ally, and they may be mounted in glycerine, or they may be 

 stained with HEematoxylin and mounted in Canada balsam. 



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 divi- 

 sion 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. 



