rRUCTIFICATION. 33 



assist the ripening of the spores, as we find certain aquatic 

 plants doing under water. The shape of the capsule, in 

 the great majority of cases, is ovate or oblong, though in 

 some genera, such as Bartramia and Pkascum, it is always 

 spherical ; in Tortula much elongated ; in Funaria pyri- 

 form or pear-shaped ; in Folytriclmm, especially when ripe, 

 quadrangular, and so on. The surface is smooth in ge- 

 neral, though there are many instances in which it is stri- 

 ated, furrowed, and dotted in various ways. As might be 

 expected, those species more exposed to vicissitudes of the 

 weather, and whose seeds are long in attaining maturity, 

 have capsules of a horny or cartilaginous substance, while 

 the Hypna and other genera growing in woods or on shady 

 banks, have them of a much slighter fabric. 



In the interior of the capsule is found the columella, a 

 small projecting thread, varying in form, and often very 

 evanescent, to which the spores seem to be attached in a 

 young state. The capsule is also lined with an inner mem- 

 brane, for the greater defence of the spores, from which, or 

 from the columella, a flat circular Hd or membrane is fre- 

 quently produced at the mouth of the capsule. 



This brings us to the external fringe or peristome, the 

 beautiful and dehcate appendage prepared by nature for the 



