CRYPTOGAMS 235 



Suggestion. Extract the chlorophyll from a mass of 

 spirogyra by placing it in a beaker and covering it with 

 alcohol. 



What change occurs in the color of the alcohol ? Remove 

 some of the plant and compare it with some which has not 

 been immersed in alcohol. 



Refer to Experiment 149. Why is the color so different 

 here from what it was there? 



Query. Does spirogyra make starch ? Does it contain 

 starch ? 



199. REPRODUCTION IN POND SCUM 

 Object. To observe conjugation in spirogyra. 



Method. In autumn procure a supply of spirogyra and, 

 having placed some in a shallow dish, examine with a mag- 

 nifier in search of the parallel filaments which have formed 

 the ladderlike structures referred to in the foregoing Experi- 

 ment. Remove such to a slide, cover with a cover glass in 

 water, and carefully examine with a low power. Look for 

 the various steps in reproduction: 



1. The ordinary cylindrical cells with their spiral chro- 

 matophores. 



2. Cells from separate filaments which have produced 

 knobs projecting towards each other. 



3. Cells in which these processes have met but not yet 

 united. 



4. Cells in which, the processes have united and their 

 dividing walls have ruptured to permit the contents of one 

 cell to flow into the other. 



5. Empty cells whose contents have gone into the con- 

 jugating cell. 



