SECT. I. THE FLOWER. 313 



some plants the pollen explodes with considerable 

 force, the cells bursting open as if by an elastic 

 spring, and dispersing it by their own spontaneous 

 action. In the Cypress-tree it is thrown out with 

 such force and in such abundance as to resemble a 

 cloud of smoke ; and if the flowers of the Birch or 

 Willow are suddenly shaken when the pollen is 

 ripe, they will exhibit a similar phenomenon. The 

 aperture by which the pollen is discharged is some- 

 times a small pore opening near the summit, as in 

 the Heaths ; but generally it is a longitudinal slit, 

 as in the Lily ; and is always effected in some de- 

 finite or determinate manner in the same species. 



The colour of the pollen is very generally white ; Its vari- 

 but sometimes it is yellow or orange, and some- et 



times it is glaucous or violet. When examined 

 under the microscope the individual particles are 

 found to assume a great variety of forms in different 

 flowers. They are often globular, oval, or cylin- 

 drical. But in the Violet they are angular ; in the 

 Narcissus they are kidney-shaped ; in the Ge- 

 r folium they are perforated ; and in the Orchis they 

 are conglomerated into masses. The surface of the 

 globules is generally smooth; sometimes it is net- 

 like ; sometimes it is wrinkled ; and sometimes it 

 is beset with prickles, as in Matoa and Hdianthus 

 animus. 



But the individual particles of the pollen are Appear- 

 themselves organized substances ; as may be seen 

 also with the assistance of a good microscope, each sc P e * 



VOL. I, I 



