36 THE NATURE AND NEEDS OF LIVING MATTER 



4. Note. The outer covering of a cell is known as a cell 

 wall, its contents is the living matter of the cell, or protoplasm. 

 The green coloring matter is chlorophyll. The protoplasm is 

 further separated into a small darker lens-shaped body, the 

 nucleus, and a surrounding portion, the cytoplasm. 



Try finding cell 

 wall, nucleus, and 

 chlorophyll in 

 your specimen. 

 Also in Figure 8. 



5. Dem. Show 

 any single-celled 

 animal of a hay 

 infusion. What 

 are the most evi- 

 dent differences 

 between these cells 

 and the plant 

 cells ? 



Conclusions. 1. Are the individual plants one-celled or 

 many-celled ? 



2. How does this plant form new plants or reproduce ? 



3. How distinguish plant cells from animal cells ? 



Note. Some special cases are difficult to decide, but do not 

 concern us now. 



4. What is a cell ? 



2. TISSUES AND ORGANS 



Method. Scrape some cells from the inside lining of the 

 cheek with a sterilized knife. Mount in water. Stain with 

 methyl green. The outer skin of a frog and onion skin may 

 also be used in the same manner. 



Observations. 1. Look for cell walls, nuclei, etc. 



2. What is the shape of a single cell ? 



3. Are the cells evidently free, or mostly united with one 

 another ? 



FIG. 8. Parts of a cell, and stages in the division of 

 a cell to form two cells. 



