240 CRYPTOGAMS 



Method. Moisten each article and place it on a plate. 

 Cover it with the bell jar and set it aside in a warm, dark 

 place. Observe any changes which may take place from 

 day to day. When molds appear, examine them carefully. 

 Where color begins to show, the spores are beginning to 

 ripen. Examine them with a magnifying glass. How many 

 different species can you find? Do the different kinds ap- 

 pear on the same or on different substances ? 



204. MOLDS 



Object. To show the mycelium of a mold. 



Apparatus. Test tubes, fruit juice, or any liquid culture me- 

 dium. 



Method. Partially fill the test tubes with the fruit 

 juice and drop into each a few mold spores taken with a 

 needle from a moldy substance. Set them in a place favor- 

 able for growth and make observations daily with a magnifier. 

 Note the minute threads which are sent forth from the 

 spores. These are called hyphce. Study the way in which 

 they spread outward and downward into the fruit juice. 

 The mass of branching and interlacing threads is called the 

 mycelium. 



How do the parts above the surface differ from those 

 below? Which ones bear spores? 



Mount the mycelium in a drop of water and study it with 

 a low power. 



205. MOLDS 



Object. To demonstrate the presence of mold spores in 

 the air. 



Apparatus. Petri dishes, nutrient solution (see page 257) mak- 

 ing it slightly acid by addition of hydrochloric acid or fruit juice 

 until it gives litmus a red color. 



