CHAPTER XIV. 
ALG. 
THE Alge form an important order of cryptogamic 
plants, comprising, however, the very simplest of all 
plants. It includes at once some of the smallest and 
some of the largest of plants, among the former being 
many of the interesting microscopic organisms re- 
ferred to briefly in Chapter I . Most of them are 
marine or freshwater plants, only a few species being 
found on land. All the seaweeds of our coasts, with 
their lovely tints and beautiful forms, are A/g@. They 
are characterised by the entire absence of ¢rue roots. 
Many of them are attached to the rocks by pseudo- 
roots; but attachment seems to be the only advan- 
tage obtained by this arrangement. Instead of being 
dependent upon these pseudo-roots for nourishment, 
they absorb it through every part of their surface. 
They are entirely cellular in their structure, though 
a few possess organs closely approaching to vessels. 
In outward form they exhibit a remarkable amount 
of variation, many of the higher forms being pos- 
sessed of thick, solid stems, like tree-trunks, as in 
Lessonia, which forms submarine forests... In the 
opposite direction, we have such forms as Protococcus, 
Desmitd, and Volvox, which consist of a single cell 
