112 PLANTS WITHOUT CHLOROPHYLL 



Conclusion. — 1. What will a parasite eventually do to the 

 host on which it lives? 



2. Why is chestnut canker an enemy to man ? 



3. W r hy is it so difficult to combat? 



Problem 88; To determine the conditions favorable for the 

 growth of mold. 



Materials. — Four wide-mouth jars or bottles, bread. 



Method. — Place a piece of bread in each of the four wide-mouth 

 bottles or jars, add a little water, and expose all four to the air of 

 the living room or kitchen for half an hour. Then cover all the 

 jars and plunge one into boiling water for a few moments ; place 

 this and a second jar side by side in a moderately warm room. 

 Place the third jar in the ice box and the fourth in a hot and dry 

 place. 



Observations. — 1. Notice day by day any changes that occur 

 in the contents of the jars. 



2. In which jar does growth appear first? 



3. Do all jars have a like growth of mold at the end of a given 

 period of time ? 



Conclusion. — 1. How does the mold get on the bread? 



2. Where does it come from ? 



3. Why did we add water to the jars? 



4. What conditions must you have for the growth of mold ? 



5. Conversely, how would you keep molds from getting a foot- 

 hold on foods? 



Problem 89: To study the structure of bread mold. 

 Materials. — Bread mold. Figure page 133, Civic Biology. 



NOTE. — Directions for Growth of Mold. — Bread mold may be conveniently 

 grown for laboratory use in small shallow dishes (Syracuse watch glasses, Petri 

 dishes, or butter chips). If bread is exposed to the air for a few minutes and then 

 left in the covered dishes for a day or two, with a bit of wet sponge or blotting 

 paper in the dish to keep the air moist, a good supply of mold may be obtained in 

 a convenient dish for observational purposes. 



Observations. — Examine the tangled mass of threads which 

 cover the bread. This is called the mycelium, each thread being 

 called a hypha. How do the hyphae appear to be attached to the 

 bread ? 





