IX 



SOME PECULIAR AND INTERESTING 

 VARIETIES OF ALGLE 



THE species of seaweeds that are known and classified are 

 said to number several thousands. These plants, which 

 have neither vessels for the conduction of fluids, nor fibers, con- 

 sisting simply of the first vegetable element, the cell, have, not- 

 withstanding this limitation, assumed a great variety of forms. 

 In size they vary from one one-thousandth of an inch in diameter, 

 the smallest green plants known, to those which exceed in length 

 the height of the tallest trees and form dense submarine forests, 

 which in places make comparatively deep water impassable for 

 boats. In texture they vary from a jelly- to a paper- and a 

 leather-like consistency. In color they have all the shades of 

 green, brown, and red. 



DIATOMS AND OTHER MINUTE ALG.E 



Among the smallest algas are diatoms. They are microscopic 

 in size, but exist everywhere in both salt and fresh water, and 

 are infinite in variety as well as in numbers. They have a sili- 

 cious, shell-like covering, which divides and subdivides in their 

 reproductive growth, forming varied shapes which are exceed- 

 ingly beautiful and interesting to examine under the microscope. 

 In vast numbers they float on the surface of the sea, and, 

 together with other minute free-floating organisms, form the 

 basis of food-supply for fishes. Their indestructible shells fall 

 to the bottom of the sea, forming large deposits, which in time 

 become fossilized. The city of Richmond, Virginia, is built upon 



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