Reproduction 



353 



dusting of flowers with pollen would not be dignified with a 

 name unless it led toward fertilization and reproduction. 



The stigmatic surfaces of the receptive flowers are 

 generally moist, and often provided with a perceptible 



FIG. 97. Pollen grains and pollen germination ; corn (a, b), apple (c), 



sweet-pea (d), and Althaea (/). 



secretion. Upon this surface the pollen may germinate, - 

 almost any pollen may germinate ; yet it usually happens, 

 from a variety of circumstances, that the pollen most 

 abundant upon any stigma is the pollen of the same 

 species. This is really what is generally implied by effec- 

 tive pollination. Strasburger, however, has made the 

 interesting discovery that upon any particular stigma pollen 

 of a plant in an entirely different family may not only 

 germinate, but may even penetrate the style to some extent. 



2A 



