PINUS 179 



at intervals along the branch. The sections 

 of the branch between these rings represent the 

 amount of each year's growth in length. Ascer- 

 tain the age of your specimen. 



(c) State several ways in which younger portions 

 of the stem may be distinguished from older. 



(d) For how many years do the dwarf branches 

 remain attached? The scales that subtend 

 them? Observe the scars left by the fallen 

 dwarf branches. 



(e) Illustrate by a drawing the features observed 

 under D, 2, (a)-(d). 



(/") Measure and record the amount of each annual 

 growth in length. 



(g) Draw a horizontal line as many decimeters long 

 as your specimen is years old. Mark off the 

 line into decimeter spaces, and at the end of each 

 decimeter erect a perpendicular as many milli- 

 meters high as the branch grew during the corre- 

 sponding year. Connect the tops of these 

 perpendiculars by a gently curving line, which 

 will be the curve of annual growth in length 

 for the period covered. 



(K) Suggest reasons for the observed differences in 

 amount of annual growth; for the direction of 

 growth taken by the branch at various times. 



(i) Make a diagram of a cross-sectional view of the" 

 branch, and describe the relative position of 

 wood, pith, and bark. Does the bark contain 

 any chlorophyll? If so, in what region is it 

 found? 



The Dwarf Branch. 



(a) Do you find nodes and internodes, or any 

 other evidence that these branches grow in 



