LABORATORY PRACTICE 



XIV. Reviewing the work done upon both roots and 

 stems, write the answers to the following questions in your 

 note-book : 



1. What differences exist between the growth of roots and 



stems as regards gravity? 



2. What differences as regards light? 



3. What differences as regards the possession of leaves? 



4. What differences as regards nodes and internodes? 



5. How, then, may we always tell a stem from a root? 



XV. Considering the different stems studied and exam- 

 ined, either in connection with the book or in addition to 

 those mentioned there, answer the following : 



1. How do we classify stems according to their structure? 



2. How do we classify stems according to their consistency 



and duration? 



3. In what different directions may stems (i.e. those above 



the ground) grow? 



XVI. Having considered the structure of several different 

 characteristic stems, we may examine them to see of what 

 service the stem is to the plant. We notice : (i) that the 

 upper part of the stem bears the leaves and carries them up 

 into the light and air; (2) that the lower part bears the 

 roots which make their way down into the ground. 



The stem serves not only to support the leaves, but also 

 as a pathway by which whatever the roos absorb from the 

 earth may be transported to the leaves and also for 

 the transfer of whatever the leaves may manufacture to the 

 roots ; in other words, it connects these two important sets 

 of organs. 



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