402 TEXTBOOK OF BOTANY 



4. Describe the arrangement of the branches and the relation 

 of the two kinds to each other. Do the branches differ in size? 

 Is a single branch of the same diameter throughout its length? 

 Which kind digests and absorbs food from the bread? By means 

 of which kind of branches does the plant spread over the bread ? 



5. Somewhat later, upright branches appear. Where do they 

 grow from ? What do they bear at the upper end? Of what use 

 are they to the plant? What is the advantage of their upright 

 growth ? 



6. As the mold grows older, what changes take place in its 

 appearance? What changes occur in the bread? What has 

 happened to the starch and other solid substances in the bread ? 



7. Mount in water a small part of a young mold plant. Ex- 

 amine a branch under the compound microscope. Is it made up 

 of small cells like a thread of Spirogyra ? Find the following parts, 

 comparing each with the corresponding part of a Spirogyra cell : 



a. The cell wall. 



b. The granular protoplasm. What is its color? 



c. Vacuoles. Are they of the same or of different sizes ? 



d. Oil drops, similar to the smaller vacuoles, but yellowish in color. 



8. Compare, with reference to all the parts named above, a 

 branch from an older mold plant. 



9. Draw on a large scale a small portion of a branch of a young 

 plant, naming all the parts. 



10. Sketch different stages in the growth of an upright branch 

 and in the formation of the spore sac at its upper end. 



11. Crush under the cover glass a mature spore sac. Note : 



a. The outer wall, which breaks under a very slight pressure. 



b. The numerous spores which have been enclosed within the wall of 



the sac. Are they aU of the same shape ? Of the same size ? 



c. The dome-shaped central portion of the spore sac, surrounded by 



a waU that is attached to the remaining basal part of the wall 

 of the sac. 



12. Study a single spore under the high power. What can you see 

 as to the structure of its wall ? Of its protoplasm ? Draw a spore. 



13. Spores may be germinated in the course of a day or two in a 

 good-sized drop of water on a shde. The slide should be kept on 



