EXERCISE 40 

 HOW DOES A DEPENDENT PLANT LIVE? 



Materials. A piece of bread or stale banana ; a glass dish with cover ; a magnifying glass. 



Directions. Moisten a piece of bread slightly and expose it to the dust of a room for an hour ; 

 then cover it to prevent drying, and put it in a warm place. If the banana is used it is treated in the 

 same way, except that it should not be moistened. Observe daily. One or more varieties of mold will 

 appear within four or five days. Describe the growth of the mold and its appearance. From what 

 source do you think it secures its nourishment ? Do you think it manufactures carbohydrates ? 



Study with a magnifier or microscope to learn more about its structure. Note particularly the 

 dustlike spores and the way in which they occur on the plant. If satisfactory observations of the 

 mold are secured under magnification, make sketches showing the structures. 



These spores are the reproductive bodies. How well are they adapted for distribution by the air ? 



Additional problems. Can you explain how the mold came to grow on the bread without anyone's pur- 

 posely planting it? 



If bread or fruit which is entirely mold-free is kept tightly closed in a mold-free container, will mold 

 develop on the bread ? 



What other kinds of plants do you know which are dependent in the same sense that mold is ? 



In what ways is the life of rusts and smuts like that of mold ? How different ? 



[52] 



