PLEUROCOCCUS VULGARIS 117 



2. Is the body of this plant differentiated into root, 

 stem, and leaves? Is it composed of cells? If so, 

 of how many? Make a thorough study of this 

 point before you answer and thoroughly consider 

 how many cells you think are necessary in order to 

 make one plant. State your opinion, with reasons. 

 Compare the arrangement of the cells with those in 

 Spirogyra. 



3. Describe the color and shape of individual cells. 

 Describe and account for any variations observed 

 in the shape of the cells. 



4. Carefully describe all the cell-organs you can 

 identify in this specimen. Name all the cell-organs 

 you cannot find. How does the chlorophyll occur 

 in the cell of Pleurococcus? If you find chloroplasts 

 state how many, their location, and relative size. 



5. Make careful drawings showing all features so far 

 as observed, with none of the cells less than 15 mm. 

 in longest diameter. 



E. Physiology: 



1. How does Pleurococcus remain fixed to the sub- 

 stratum on which it grows? Are there special 

 organs for this purpose? 



2. Are there special organs for the taking in of nourish- 

 ment from the substratum? How can the plant 

 accomplish this process? 



3. Is photosynthesis possible with Pleurococcus? Give 

 reasons for your 'answer. Are stomata present? 

 Why? Describe how CO 2 can be taken into the 

 cell. 



4. Are there any special organs of respiration? How 

 can this process take place? 



5. Do you think Pleurococcus is sensitive to stimuli 

 from without? Give reasons for your answer. 



