52 MANUAL OF NATURE STUDY. 



planted on blotting paper, or on cotton in a tumb- 

 ler of water. These may be seen, however, very 

 well without a hand lens. 



Our next attention is to the leaf. Do roots and 

 flowers have to do all the work there is to be done 

 in the seed factory ? What are leaves for ? If a 

 leaf, the under side of it, should be covered with 

 dirt, what change in color would that part of the 

 plant undergo? Did you ever see the corn-blades 

 and maple leaves covered with dust from the road 

 during dry time in August or September ? What 

 effect did the dust have upon the thriftiness of the 

 plants ? Did you ever wash the leaves of your 

 house plants ? Why did you do so ? Could you 

 breathe as well with your nostrils filled with dust ? 

 The nostrils, or stomata of plants, are most 

 numerous on the under side of the leaf. Do 

 you now see why the leaves should be kept 

 clean ? Does breathing air have anything to do 

 with the growth of our bodies? How? Does 

 breathing air and moisture have anything to do 

 with the growth of the plant ? Then does the leaf 

 have anything to do in helping the flower to make 

 seeds? 



Call attention to the many thousand mouths 

 (stomata) of the leaf, and the fact that each little 

 mouth is opened and shut at exactly the right time; 



