SECT. iv. SPH^EROPHOREI. 311 



columella. The sporidia are beautiful objects under the 

 microscope on account of their spherical form, which is 

 rare among lichens, and their more or less deep blue tint 

 a colour by no means peculiar to the sporidia of this 

 order of plants, for in other orders they are bright 

 scarlet, olive, golden yellow, or brown. 



