130 . FOOTNOTES FROM 



year in duration, many of them dying in the course of a 

 few months or weeks. They complete the process of 

 reproduction early in spring, and last during the 

 summer, perishing in the autumn, and disappearing 

 altogether in winter. No sooner does the ice, which had 

 bound up the streamlet in its silent fetters, melt under 

 the warm rays of the sun, allowing its water to flow 

 merrily on, and flash and sparkle in the sunbeams, than 

 every stone in its bed, though brown and naked before, 

 is suddenly, as if by magic, invested with a green velvet 

 coating, whose long graceful filaments float freely with 

 the water. Every ditch and marsh, every rivulet of 

 water, every hoof-mark and rut on the road where water 

 has accumulated, is filled with green clouds of these 

 mysterious plants. The purposes which they serve in 

 these situations are sufficiently obvious. Though asso- 

 ciated in our minds with stagnation, putrefaction, and 

 malaria, they are the scavengers, the water-filters of 

 nature. Like the flowers and the trees, which on dry 

 land remove the impurities with which the animal world 

 is continually tainting the atmosphere, they purify the 

 waters in which they occur, by assimilating the decaying 

 matter which they contain ; while their own tissues form 

 food and shelter to myriads of animalcules, which wander 

 over these to them trackless fields and endless mazes, 

 and convert the waste pools and ditches of the wayside 

 into scenes of busy life and enjoyment. This perfect 

 adjustment in the economy of the animal and vegetable 

 kingdoms, whereby the vital functions of each are main- 

 tained in the utmost efficiency, is one of the most beauti- 

 ful and striking phenomena of organic nature. 



