94 REPRESENTATIVE PLANTS 



1. The rounded structures (cells) are the individual 

 plants. Are they equal in size? Observe a clear, outside 

 layer {cell icall) and the green-stainod interior {cytoplasm 

 colored with chlorophyll.) 



2. Observe that some single cells are oblong in form. 

 What do you conclude from these observations? 



8. By moving the slide, discover, if possible, forms with 

 partitions, dividing them into two, three, or four parts. 



Observe, further, that these combinations vary much in 

 the completeness of the division into cells. This shows 

 how pleurococcus reproduces and is called cell division. 



Cell division. Cell division is the simplest manner by 

 which a plant can reproduce itself. It is simply the division 

 of a cell into two parts that may or may not remain tem- 

 porarily attached. This division may be repeated for a 

 greater or less number of times. 



Drawings and description. Make drawings showing all the 

 results of your observations, and remember that all drawings 

 are to stand the test of neatness, accuracy, clear outlines, and 

 proper naming. Write a careful description, embodying in 

 it answers to ail the questions asked in the preceding 

 sections. 



Green plants. Green plants, i.e. those which contain 

 chlorophyll, are able to secure or make their own food from 

 the mineral substances that are in the earth, water, or air. 

 Such plants are independent. Apply this statement to the 

 pleurococcus. Where is the food su})ply taken from? 



An alga is a plant of very simple structure containing 

 chlorophyll, usually living in the water. Our plant is an 

 alga. Do its observed habits bear out this statement ? In 

 all places that you find the plant growing, what can be said 

 about it ? (Refer to habitat.) 



3. Algae have various colors, the color due to chlorophyll 

 being often obscured by other tints. Pleurococcus, how- 

 ever, is true chlorophyll green. 



