232 PKACTICAL BOTANY 



close to the apex of the shoot of the current year. They 

 are few in number : their structure has already been 

 observed : each may develop into an unlimited axis. 



It may here be observed that both (a) and (6) have a 

 similar origin, both being axillary buds in the axils of 

 the leaves of the main axis of the current year. The 

 apparent difference depends upon the fact that the buds 

 (b) are more strongly developed than (a). 



II. Passing to the increments of growth of formei 1 

 years, i.e. to the lower and older parts of the branch, 

 in the external appearance and arrangement of parts 

 they resemble that of the current year. The main 

 axis increases in thickness, and is more obviously 

 ligneous, while the bifoliar spurs drop off, leaving scars 

 which mark their former position. 



THE STEM. 



It is best to work with material which has been treated for 

 some time with spirit ; by this means the resin, which would 

 otherwise clog the razor, is removed. 



I. Cut transverse sections of the axis of a bud, and 



treat with dilute potash for a few minutes : mount in 

 glycerine. 



Meanwhile other sections may be mounted in chlor- 

 zinc-iodine : examine with a medium or low power, and 

 observe at the centre of the section 



1. The pith, composed of cells with intercellular 

 spaces, and thick cellulose walls (blue with chlor-zinc- 

 iodine) : surrounding this a series of groups of smaller 

 constituents : these are 



2. The primary vascular bundles. Note that they 



