52 



FUNCTIONS OF LIVING THINGS 



NOTE. — If a sperm cell reaches a large cell (called an 

 egg) located in the oviile, the sperm and the egg unite to 

 form a single cell. The egg cell is then said to be fertilized. 

 This process is known as fertilization. After fertilization 

 the egg will grow into a tiny structure known as an embryo. 

 The ovxile then is known as a seed. The embryo within the 

 seed will, under favorable conditions, develop into a young 

 plant. 



Conclusion. — 1. What is fertilization and 

 how does it take place ? 



2. What results from fertilization of the egg 

 of a flower? 



3. Why are the stamens and pistils called 

 essential organs? 



4. Why is the process of fertilization nec- 

 essary ? 



1, pollen grain ; 2, at 

 time it falls upon 

 stigma ; 3, starting 

 to grow ; 4, with a 

 pollen tube; s, 

 sperm cell nucleus. 



Problem 23 



fojnned. 



To discover how fruits are 



a. The Bean 



Materials. — Pea or bean flowers, bean pods. 

 Diagram, page 55, Civic Biology. 

 Method and Observations. — Examine an unopened pod. 

 Compare it with the pistil of an old flower. Find the ovary or 

 seed case, the style, and the stigma. Open the pod. Notice the 

 little seeds. How are they attached to the pod? Why are not all 

 the seeds the same size? (Look up the diagram on fertilization.) 

 Conclusion. — 1. What part of the flower forms the bean fruit? 

 2. What is one use of a fruit to the plant? 

 Drawing. — Draw an opened pod showing the seeds. Label 

 all the parts. 



b. The Apple 



Materials. — Apple blossoms in various stages, or chart. 

 Apples. Diagram, page 56, Civic Biology. 



Observations. — In an apple blossom how are the sepals placed 

 with reference to the ovary, above or below it ? Note the position 

 and appearance of the receptacle, or base, of the flower. 



Observe several young apples in different stages of develop- 



