THE CLASSES OF ALG. 85 
of the colossal forests of Sargasso in the Atlantic ocean, those 
immense banks of Algze, covering a space of about 40,000 
square miles—the same which made Columbus, on his voyage 
of discovery, believe that a continent was near. Similar but 
far more extensive forests of Aloz grew in the primeval 
ocean, probably in dense masses, and what countless genera- 
tions of these archilithic Aloz have died out one after 
another is attested, among other facts, by the vast thickness 
of Silurian alum schists in Sweden, the peculiar composition 
of which proceeds from those masses of submarine Algz. 
According to the recently expressed opinion of Frederick 
Mohr, a geologist of Bonn, even the greater part of our coal 
seams have arisen out of the accumulated dead bodies of the 
Algze forests of the ocean. 
Within the branch of the Algze we distinguish four 
different classes, each of which is again divided into several 
orders and families. These again contain a large number of 
different genera and species. We designate these four 
classes as Primeval Alove, or Archephycez, Green Algze, or 
Chlorophyceze, Brown Algve, or Pheeophycee, and Red Alez, 
or Rhodophyceee. 
The first class of Algze, the Primeval Algze (Archephyceee), 
might also be called primeval plants, because they contain 
the simplest and most imperfect of all plants, and, among 
them, those most ancient of all vegetable organisms out of 
which all other plants have originated. To them therefore 
belong those most ancient of all vegetable Monera which 
arose by spontaneous generation in the beginning of the 
Laurentian period. Further, we have to reckon among them 
all those vegetable forms of the simplest organization which 
first developed out of the Monera in the Laurentian period, 
