PROTECTION OF THE POLLEN. 329 



panula, and others, while the over-shadow- 

 ing corolla keeps oft' rain, the air has free ac- 

 cess underneath to blow the pollen to the 

 stigma. Nor is this drooping caused by the 

 wei<dit of the flowers, for the fruit in most 

 of them is much heavier, and yet stands 

 erect on the very same stalk. The papi- 

 honaceous flowers in general spread their 

 wings in fme weather, admitting the sun and 

 air to the parts within ; whereas many of 

 them not only close their petals at night, but 

 also derive additional protection from the 

 green leaves of the plant folding closely about 

 them. Convolvulus arveusix, t,Si'2, Ana- 

 gallis arvcnsis, t. 5'29, CakiuJula pluvlalls, 

 and many others, are well known to shut up 

 their flowers against the approach of rain; 

 whence the AnagalUs has been called the 

 Poor Man s Weather-glass. It has been ob- 

 served by Linna'us that flowers lose this fme 

 sensibility, either after the anthers have per- 

 formed their oflice, or when deprived of them 

 artilicially ; nor do I doubt the fact. I have 

 had reason to think that, during a long con- 

 tinuance of wet, the sensibility of the Ana- 

 galUs is sometimes exhausted ; and it is evi- 



