256 HISTORY OF BRITISH FERNS. 



oval form, having four elastic filaments, thickened at the ends, 

 coiled around them. These, when the spore has become 

 ripe, unroll; and their elasticity, no doubt, contributes to 

 burst the case in which the spores are contained, as well as to 

 assist in the dispersion of these minute reproductive bodies. 

 They are, indeed, so irritable, that a change of temperature 

 or moisture, such as that produced by breathing on the 

 spores, is sufficient to produce this forcible uncoiling. The 

 spores themselves are very interesting microscopic objects ; 

 indeed, it is only under a high magnifying power that their 

 nature can be examined. 



The germination of the spores has been made the sub- 

 ject of experiment by several inquirers, whose observations 

 have been published. Agardh states, that from three to 

 fourteen days after the spores are sown, they send down a 

 thread-like transparent root somewhat thickened at the end, 

 and protrude a confervoid, cylindrical, obtuse, articulated, 

 torulose thread, which is either two-lobed or simple at the 

 apex. Some days after this, several branches are produced, 

 and become agglutinated together, forming a body resem- 

 bling a bundle of confervoid threads, each of which pushes 

 out its own root. Bischoff finds these confervoid threads 

 go on growing and combining until a considerable cellular 



