EXERCISE 114 



Problem. How does conjugation take place in a simple plant ? 



What to use. Microscope ; slides and cover glasses ; pond scum Spirogyra. 



What to do. Mount Spirogyra and examine with microscope, to learn the structure of the cell, the 

 nucleus, and the chlorophyl band. Bits of Spirogyra from the bottom of the jar, when they begin to 

 change color, should be examined for conjugation stages ; these will be recognized by the fact that two 

 threads lie close together, with outgrowths reaching across, forming a ladder-shaped arrangement. Note 

 any changes going on in any part of the cell. 



Record. With the aid of diagrams describe the stages found and the end result. 



Questions. 1. Are all the empty cells in one thread, or are there some empty cells in each thread ? 



2. Are the cells of one thread (before conjugation) distinguishable from those of the other thread - 

 in size, in structure, in color, or in any other way ? 



3. How does the zygote resulting from conjugation differ from a spore ? 



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