THE PA GE OF NA TUBE. 1 3 1 



The largest of the fresh-water algse is the River 

 Leinania (Lemania fluviatilis). It is never found 

 growing in stagnant waters ; indeed, it is said to languish 

 and die, when the streams in which it is produced have, 

 by some cause or other, been converted into motionless 

 pools. It loves to grow in clear swift rivers, flowing with 

 a strong current over a rough and rocky bed, and in 

 Alpine streamlets, on the very verge of the numerous 

 cascades which they form during their descent from the 

 hills. It is a matter of surprise how it can sustain the 

 immense force and weight of the impetuous waters, with- 

 out being uprooted and carried away. Examination willj 

 however, discover that it has been wonderfully provided 

 with means to enable it to brave the dangers to which 

 in such situations it is exposed. Its filaments are elastic, 

 rigid, and bristly, from three to six inches in length, 

 v about the size of a hog's bristle, and knotted throughout 

 at equal distances with prominent swelling joints, like 

 those of the bamboo cane. They spring from a tough 

 cartilaginous disk, so firmly applied to the rock as to 

 require a very considerable force to detach it. It is 

 impossible to convey in words, the same strong impres- 

 sion of fitness and perfection of contrivance, which a 

 glance at the plant in its native haunts would produce. 

 It appears one' of the most striking examples of that 

 compensatory adaptation of structure to requirements, 

 which we observe more or less in all the lowest plants ; 

 in the moss, which, considering its size, adheres with 

 more tenacity to its growing place than the oak of 

 centuries, that strikes out its roots over half an acre of 

 ground ; and in the minute crustaceous lichen, apparently 



