POLLINATION AND SEED FORMING 211 



different act of fertilization. If the pollen is transferred 

 from the anther to the stigma of the same flower, it is 

 called close or self-pollination. If the pollen is trans- 

 ferred from the anther of one flower to the stigma of an- 

 other, it is called cross pollination. With a sharp knife 

 cut an ovary in two across the middle. What do you find 

 on the inside? Those tiny seedlike bodies are called 

 ovules. 



Have children watch the development of a flower from 

 the time it opens until the seed is ripe. What parts of the 

 flower wither and drop off ? What parts remain ? What 

 part becomes the seed pod ? What part becomes the seed 

 or seeds? 



Problem. — Is pollination necessary to produce seeds? 



If plants are growing near the school select some 

 nasturti.um flowers that are just opening and carefully 

 remove the stamens with a pair of sharp-pointed scissors, 

 then cover the flower with a paper bag so that no pollen can 

 be conveyed from other flowers to the stigma. Treat 

 another flower in the same way, but leave the paper bag off. 



Leave the bag on for a week or ten days, then remove 

 and note conditions. Cover enough flowers in this way so 

 that there can be no doubt in the minds of the pupils as to 

 results. If there are no plants near the school, have some 

 of the reliable pupils start the experiments at home and 

 bring the plants to school for observation and study. 



What are the agents that aid in transferring pollen 

 from one plant to another ? Have pupils watch the insects 

 that visit flowers or draw upon their observation and 

 experience. They will probably know also that the wind 

 as well as insects is an agent of pollination. 



