IX 
SOME PECULIAR AND INTERESTING 
VARIETIES OF ALGAL 
HE 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 tor 
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 
Among the smallest alge 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 
32 . 
