400 TEXTBOOK OF BOTANY 



g. A thin film of slimy cytoplasm just outside the nucleus. 



h. Strands of slimy cytoplasm running in all directions from the layer 



about the nucleus to the layer just within the wall. 

 i. The central vacuole. What is its shape ? What does it contain ? 

 j. Draw very carefully a single cell, naming all the parts. 



6. Place a number of plants in alcohol in a test tube. Close the 

 end of the tube with a cork and set it away. Examine it the next 

 day. Is the alcohol colored? Lift the plants out of the alcohol. 

 Are they still green ? 



7. Examine one of these plants under the microscope. Are the 

 chloroplasts still present in the cells ? What is the relation of the 

 chloroplasts to the green coloring matter (chlorophyl) ? What has 

 happened to the chlorophyl ? 



8. In a large glass jar that stands in a sunny place and contains 

 a vigorous culture of Spirogyra in water, completely immerse an 

 inverted funnel, so that all the plants are held within or below 

 the larger end of the funnel. Invert a test tube full of water so 

 that its open end fits over the neck of the funnel, and fasten the 

 tube in this position. The bubbles of gas formed by the plant 

 will rise and replace the water in the test tube. When the tube is 

 filled with gas, remove it and insert into it a glowing match or 

 splinter. If the experiment is successful, the glowing end of the 

 match or splinter will burst into flame. What does this show as 

 to the nature of the gas in the test tube ? How was this gas pro- 

 duced by the plant ? 



9. Determine by a similar experiment whether or not the same 

 gas is produced by plants kept in darkness. 



10. If living plants in process of conjugation are available, they 

 should be used for the following study. Otherwise, material pre- 

 served in alcohol or formalin may be used. Notice that two plants 

 place themselves parallel for part or all of their length. Study the 

 following steps in the process of conjugation : 



a. The appearance of a, swelling on the side of each cell which is 



turned toward the other plant. 



b. The growth of these swellings from two cells, one in each plant, 



until they touch each other. 



c. The disappearance of the walls of the swellings at the point where 



they meet ; the two swellings now form a continuous conjuga- 

 tion tube. 



