PINE STEM 135 



3. In the axils of these, especially at the upper part of the 

 internodes, are axillary buds of two kinds. 



(a) Buds with limited growth (bi foliar spurs), each bear- 

 ing two acicular foliage-leaves, surrounded at the base with 

 numerous scale-leaves. These dwarf foliage shoots occur in 

 the axils of the scales throughout the greater part of the 

 current year's growth : in older parts they may be found to 

 have fallen off, the bifoliar spurs separating as a whole from 

 the parent branch. 



() Buds with unlimited growth, which are seated 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 (a) and (b) 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 former years, 

 i.e. to the lower and older parts of the branch, in the ex- 

 ternal 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 young elongating shoot of 

 the current year taken in June : mount some in glycerine, others 

 in chlor-zinc-iodine : the sections have a wavy outline, the in- 

 dentations corresponding to the grooves which may be observed 

 externally. Starting from the periphery of the section, note the 

 following tissues : 



i. Epidermis, a single layer of cells, following the wavy out- 



