134 PRACTICAL COURSE IN BOTANY 
the bud. These scars are sometimes very persistent, and 
in the common fig and magnolia may often be traced on 
stems six to eight years old. Do they furnish 
any indication as to the relative age of the 
different parts of the stem, like the bands of 
scars on twigs of horse-chestnut and hickory ? 
Give a reason for your answer. (Fig. 152.) 
150. Different rates of growth. — Notice 
the very great difference between branches 
in this respect. Sometimes the main stem 
will have lengthened from twenty to fifty 
centimeters or more in a single season, while 
some of the lateral ones will have grown 
but an inch or two in four or five seasons. 
F10.152.—-Stem One reason for this is because the terminal 
of tulip tree: s,s, bud, being on the great trunk line of sap 
scars left by stipular 3 
scales: l,l,leaf scars. NMovement, gets a larger share of nourish- 
ment than the others, and being stronger 
and better developed to begin with, starts out in life with 
better chances of success. 
Make a drawing of your specimen, showing all the points 
brought out in the examination just made. Cut sections 
above and below a set of bud scars and count the rings of 
annual growth in each section. What is the age of each? 
How does this agree with your calculation from the number 
of scar clusters left by the bud scales? 
151. Irregularities. —'Take a larger bough of the same 
kind that you have been studying, and observe whether the 
arrangement of branches on it corresponds with the arrange- 
ment of buds on the twig. Did all the buds develop into 
branches? Do those that did develop all correspond in size 
and vigor? If all the buds developed, how many branches 
would a tree produce every year? 
In the elm, linden, beech, hornbeam, hazelnut, willow, and 
various other plants, the terminal bud always dies and the 
one next in order takes its place, giving rise to the more or 
