16 AGRICULTURE 



flowers. While it is in the blossoms, it usually happens 

 to brush against the sticky or rough stigma, which catches 

 some of the pollen it brings. It is interesting to watch 

 the movements of the insects when they are thus helping 

 the flower to form seed. 



Gardeners who grow tomatoes in the greenhouse col- 

 lect the pollen and place it on the flowers by using a brush 

 (Fig. 15). If they fail to do so, they get very few 



Court**; Mirh Expt Station 



FIG. 15. POLLINATION or TOMATOES 



The two on the right grew from pistils abundantly supplied with pollen; the two 

 on the left from pistils receiving but little pollen. 



tomatoes. If there were many large insects in the green- 

 house, they might not need to take this trouble. We do 

 not need to practice this hand pollination when tomatoes 

 are grown in the garden, for then insects might do this 

 useful work instead of human hands. 



In one locality the fruit-growers thought that bees were 

 injuring their ripe fruits, and accordingly made the keepers 

 of bees remove their hives. As a result, the fruit crop de- 

 creased. Then the bees were brought back, and the crop 



