CHAPTER III 



THE CONNECTION BETWEEN STRUCTURE AND FUNCTION 

 I. A STUDY OF THE CELL AND OF PROTOZOA 



To show what Single Cells can Do 



Materials. 



Some single cells of plant or animal tissue, stained to 

 show structure. Slides of a one-celled animal, stained. 

 Living one-celled animals. 



Definitions. 



Cell, the smallest living unit. 



Protoplasm, the living material composing the cell. 



Nucleus, a dense bit of protoplasm, usually near the cen- 

 ter of the cell, often staining dark. 



Cytoplasm, the less dense protoplasm outside of the nu- 

 cleus, usually taking a lighter stain. 



Nucleolus, paranucleus or micronucleus, a very small, 

 dense, dark-staining body, either within the nucleus (nu- 

 cleolus) or near it (paranucleus or micronucleus). 



Cell wall, the lifeless membrane surrounding many cells, 

 secreted by the protoplasm. 



Food balls, bits of food inside the cells of many one-celled 

 animals, usually showing through the walls. 



Food vacuole, a small drop of water containing diges- 

 tive material and a food ball. 



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