of Ocean-weeds 



one. Diatoms lived and died in ages gone by, 

 and their remains are found hardened into flint. 

 Diatoms live and die in these days ; and their 

 remains may yet, in centuries to come, be trans- 

 formed into the same substance. 



From Diatoms one might range upward through 

 an enormous variety of Ocean-weeds, of all kinds 

 and descriptions. 



Though they are the ''last and lowest of all 

 the tribes of plants," yet it is a wide step from the 

 undermost to the uppermost of even this humble 

 Veofetable Tribe. 



At least five or six thousand species of Sea- 

 weeds are known to Naturalists. Each ocean, 

 each lesser sea, has its own particular vegetation, 

 largely affected by the varying degrees of salt- 

 ness, the warmth or coldness of the water, and 

 the faster or slower currents which happen there 

 to prevail. 



Sea-weeds of all sizes are found, from the in- 

 visible diatoms to enormous growths in Pacific 

 waters, reaching to yards upon yards in length, 

 with solid trunk-like stems, and huge fronds like 

 those of a tropical palm. 



Near Tierra del Fuego immense growths have 

 been seen, with stems between three and four 

 hundred feet in length. Great sub-ocean forests 



159 



