116 A TEXT-BOOK OF BOTANY 
by other colors, and the plants have a characteristic grass- 
green color. As indicated by the illustrations given above, 
they include simple one-celled forms which reproduce only 
by cell-division (vegetative multiplication), and simple 
or branching filamentous forms which also reproduce by 
swimming spores and odspores. Such filamentous forms 
as Ulothrix, Cladophora, and Gidogontum are representa- 
tives of a group known as the Conferva forms, having 
bodies of many cells and swimming spores. Vaucheria 
represents the large group of Stphon forms, characterized 
by their ccenocytic bodies. Spirogyra represents the Con- 
jugate forms, the name meaning “yoked together,” and 
referring to the connecting of the filaments for fertilization; 
the group is characterized also by the absence of swimming 
spores and the peculiar chloroplasts, not all of which are 
spiral bands. 
The bodies of green Algze are not all single cells or 
filaments, the marine sea-lettuces, belonging with the 
Conjerva forms, having broad, flat, leaf-like bodies that 
have suggested the common name. Some of the green 
Algee are associated with the blue-green Alge in the pol- 
lution of water reservoirs referred to in § 62. 
3. Brown Auc.© (Pheophycee). 
71. General characters.—The two preceding groups are 
the most common Algz of the fresh waters, but the brown 
Algee are almost all of them marine. The association of a 
brown coloring matter with the chlorophyll has given name 
to the group, and the plant bodies display various shades of 
yellow, brown, or olive. In size the brown Alge range 
from forms that are microscopic to those that are hundreds 
of feet long. They belong chiefly to the colder waters of 
the globe, reaching their greatest development in the arctic 
and antarctic regions, The greatest displays of huge bodies 
