94 SEA-WEEDS. 



of these sea-weeds, in their turn, renews the soil 

 of ocean bed, by means of which it gradually rises. 

 And thus the lovely and picturesque plants of the 

 sea aid with the rushing of the waters, and ebbing 

 and falling tides, and with the saltness arising from 

 the deposits of saline matter in the channels of the 

 deep, to change what else would be evil into good, 

 and to spread purification and wholesome air, in- 

 stead of poison. 



The number of British sea-weeds is about three 

 hundred and seventy, and of these many need the 

 aid of a microscope to discover their beauty of 

 structure. Growing both in salt and fresh waters, 

 or forming crusts on rocks, or sea-caves, or on in- 

 land moist places, are to be found tribes of Algce, 

 which seem formed of little riband-like particles, 

 which, when subjected to microscopic investigation, 

 startle and puzzle the philosopher, at one moment 

 appearing to have animal, and at another vegetable 

 life; or resolving themselves into those links be- 

 tween the two kingdoms, those tribes, half plant, 

 half animal, which, until the recent improvements 

 in the microscope, have lived through countless 

 generations, unknown and unsuspected. Some of 

 the Oscillatoria tribe are found in salt waters, for 

 they exist wherever there is water, though more 

 abundantly in ponds or rivers, or on moist places, 

 than in the sea ; and naturalists know not whether 

 to regard them as plants or animals. Adanson 

 was the first who discovered their singular move- 

 ments, which have since much interested men of 

 science. They often form crowds of filaments of 

 greenish or brownish tint, each pellucid thread 

 having a diameter of about the thousandth part of 

 an inch. Now they assume the crooked windings 



