PINUS. VEGETATIVE ORGANS. 137 



the axils of these will be seen the axillary buds above noted. The 

 main axis of the bud has become elongated by extension of the 

 tissues. 



In studying the growth of the current year, bear in 

 mind that it has been derived from a bud, which had a 

 similar structure to that which is now seated at its 

 apex. Examine the stem of the current year externally, 

 and note 



1. The thick Main axis, more or less succulent in 

 appearance; its surface is marked by longitudinal 

 grooves. 



2. The brown tooth-like bases of the scale-leaves 

 of the bud, best seen at the lower part of the 

 intern ode. 



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, each bearing two 

 acicular foliage leaves, surrounded at the base with 

 numerous scale-leaves. These limited foliage shoots 

 occur in the axils of the scales throughout the greater 

 part of the current year's growth. 



b. 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 both 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. 



