100 ELEMENTARY STUDIES IN INSECT LIFE 



ulus not only causes tlie seed to grow, lint also 

 the surrounding 1 fruit, the latter depending upon 

 seed development in most cases. In some cases, how- 

 ever, the growth of the pollen tube may help to 



FIG. 78. Bartlett pear cross-pollinated with the pollen of the Easter pear. 



stimulate the fruit to develop independently of the 

 fecundation of the ovule, which may or may not after- 

 wards result, and this probably accounts for the fact that 

 many little fruits begin to develop, but afterwards drop 

 off."' 



