STEMS 373 



For this reason the planting of certain. trees near sewer pipes 

 is often prohibited. 



Experiment 114. Boil some water so as to drive out the air and 

 after it has become cool fill a 2-quart fruit jar half full. Dissolve 

 in this all the necessary plant food as was done in Experiment 

 108, making the solution the same strength. Place in this a slip 

 of Wandering Jew. Pour over the surface of the water a layer 

 of castor oil or sweet oil. Place this jar alongside the slip in the 

 other complete food solution, Experiment 108. Both slips have 

 the same conditions except that the oil keeps out the air from the 

 roots of one of them. Does the absence of air affect the growth of 

 the slip? 



As the tips of the roots are delicate, it can be readily seen 

 that if they are to grow readily the soil around them must 

 be mellow. It was seen in Experiment 114 that if roots 

 are to grow they must have air, another reason for keep- 

 ing the soil mellow. 



Roots are, however, not simply absorbers of water and 

 dissolved food. Some of them act as storehouses for the 

 food that the plant has prepared for future use. Beets, 

 carrots, parsnips, turnips, and sweet potatoes are examples 

 of roots which store food ready for the rapid growth of 

 the next year's plant. 



Stems. Experiment 115. Examine a corn stalk. Notice how 

 and where the leaves are attached to the stem. Do the alternate 

 leaves come from the same side of the stem? Cut a cross section 

 of the stalk. Notice the outside hard rind, the soft pithy material, 

 and the small firmer points scattered about in the pith. Cut a 

 section lengthwise of the stalk and notice how these small firmer 

 points are related to the lengthwise structure of the stem. 



Cut off a young growing corn stalk and place the cut end in 

 water colored by eosin or red ink. Allow it to stand for some time 

 and then cut the stalk off an inch or two above the surf ace of the 

 water. How have " the firmer points " been affected? If possible, 



