FLORAL MECHANISMS 89 



humming-birds. The mechanism acts precisely 

 like that of the iris, scraping pollen from an 

 ar r i v ing 

 humming- 

 bird, but 

 closing as 

 he with- 

 draws with 

 home- 

 grown pol- 

 len on his 

 head. 



TRUMPET VINE 



The trum- 

 pet-creeper illustrates a principle in the fertilisa- 

 tion of flowers which we should point out. I have 

 noticed that our own trumpet-vine rarely sets any 

 seed-pods, and find in this fact the illustration of 

 a principle in the fertilisation of flowers which 

 should be explained. 



In general, flowers are more easily fertilised by 

 pollen taken from the flowers of another plant 

 less sensitive to pollen taken from another part of 

 their own plant, and scarcely sensitive or entirely 

 sterile to pollen taken from their own anthers. As 

 a demonstration, Fritz Miiller fertilised a Brazilian 

 species of the Bignonia, which is the family name of 

 our trumpet-creeper, with the following result: 



