20 UISTOllY OP BRITISH PEIUv^S. 



great abundance of seed-like bodies, wliich are technically 

 called spores, and are contained in little cases of very sin- 

 gular construction. Collectively, these cases and their 

 contents are called i)\e fructijication. The seed-cases, as 

 already remarked, are attached in the different species to 

 certain determinate thickened portions of the veins, which 

 points of attachment arc called the receptacles. Each 

 separate mass or cluster of the seed-cases is called a sorus, 

 but as they are generally spoken of collectively, the plural 

 term sort becomes much more frequently used. The sori 

 are maniinal when they grow out from the margin, and 

 dorsal when they occupy some part of the under surface of 

 the frond. 



The seed-cases — called also spore-cases, or sporanci'ia, or 

 tJieccu — are mostly minute roundish-oval bodies, containing 

 one cavity, and nearly surrounded by a jointed vertical 

 band called a ring, which is continued from the base so as 

 to form a short stalk, by which they are attached. ^Vhen 

 they have reached maturity, the elasticity of the ring bursts 

 the case by an irregular transverse fissure, and the seeds 

 or spores, in the shape of fine dust, almost invisible, become 

 dispersed. This is Avhat occurs in the majority of the natiA^e 

 species. In 2'richomanes and Hiimenoph>jllum, however, 



