50 BUILDING MATERIAL OF LIVING THINGS 



through the assimilation of food materials, a cell has grown to a 

 certain bulk, fixed in each form of animals and plants, the nucleus 

 divides. The chromosomes divide, an equal number going to each 

 new nucleus. Then the cell body divides, and two smaller cells 

 result. This is cell division. 



Problem Questions 



1. Where and how does growth take place in the body of a plant or animal? 



2. In what respects are plant and animal cells alike? How are they dif- 

 ferent ? 



3. Why do cells divide, instead of growing larger and larger in size? 



4. What is protoplasm ? Whj^ can we not see it in our bodies ? 



5. What changes take place in the cell when it divides ? Study the dia- 

 grams carefully. 



6. What kinds of tissues can j^ou find in your own body without the use of 

 the compound microscope ? Can you find any plant tissues ? 



Problem and Project References 



Hunter, Laboratory Problems in Civic Biology. American Book Company. 



Densmore, General Botany. Ginn and Company. 



Locy, Biology and Its Makers. Henry Holt and Company. 



Newman, Outlines of General Zoology. The Macmillan Company. 



Wilson, The Cell in Development and Heredity. The Macmillan Company. 



