114 STEMS 



Do they have nodes? How many leaves to each node? 

 How many axilLary buds to each node? How does maple 

 resemble lilac? How does maple differ from ailanthus and 

 beech? Which plants have prominent nodes ? Which have 

 least conspicuous nodes ? 



Conclusion. Of what unit does every stem consist ? 



Note. A stem may be considered as being made up of the sum 

 total of its nodes and internodes. The unit of plant gross structure 

 is the internode with one node. 



Note. When a seed is dissected, its embryo is found to consist 

 of a single internode (the hypocotyl) and one node bearing one or 

 more seed leaves with a growing point (the plumule) between them. 



Growth therefore consists of the multiplication of these units 

 as the plant is built up. 



Gross structure is resolvable into internodal units, just as fine 

 structure is resolvable into tissues and cells. 



108. STRUCTURE 



Object. (a) To learn the gross structure and character- 

 istics of a cornstalk. 



(6) To learn something of the ~*ine structure of a corn- 

 stalk. 



Apparatus. Some sections of cornstalk long enough to show 

 the joints or nodes. 



(a) Method. Examine the outside and note the rind 

 or skin which covers it, the prominence of the joints, and the 

 groove on one side which shows where a branch was. 



Examine the cut-off end and note the compact region near 

 the rind, the loose pith which fills the bulk of the stem, and 

 the woody fibers which are scattered through it. Draw. 



Cut a section lengthwise to see how these fibers run and 

 how a section at a joint differs from the other portions. 



