212 THE TEACHING BOTANIST 



IV. The storage system. 



All of these systems are to be worked out with 

 simple lens and scalpel. 



37. In the young woody stem, what systems may be 



distinguished ? 



38. Construct diagrams showing by colors the dis- 



tribution of tissues in the plant through shoot 

 and root. 



Materials. Balsam (Impatiens sultani} is easy to raise, 

 and very good for this use because of its translucent stem, 

 which renders the fibre-vascular system very distinct, though 

 the distribution of its green tissue in the stem is not as sharply 

 differentiated as usual. Coleus is also very good, and almost 

 any herbaceous plant will do. For Exercise 37 any young 

 woody twigs are good, but those with a greenish bark are best. 



Pedagogics. One of the most useful of exercises upon an 

 important phase of anatomy (i.e. the contact of, and transition 

 from, the visible to the invisible) commonly overlooked. It is 

 extremely good for training in minute observation, and also as 

 knowledge, for it gives a good comprehensive idea of the dis- 

 tribution of tissues and of the relation of invisible to visible 

 features likely to be missed in an exclusively microscopic 

 study. Far more of minute anatomy can be traced out with 

 the hand lens than is commonly supposed. It also gives, far 

 better than a microscopic study, an understanding of the 

 general physiological uses of the different tissue systems. For 

 best work on this subject the students should previously in some 

 demonstration or lecture have had their attention called to 

 the general physiological conditions which plants must take 

 account of, protection against drying up, against animal 



