COLEOCHAETE 313 
tion the odspore forms four zoéspores, each of which develops a 
new filament. In some forms of Oedogonium there are both 
male and female filaments. In some species the male plants are 
miniature filaments and attach themselves to the female plants, 
where they produce sperms in their terminal cells. 
Coleochaete. — This form (Fig. 269), found growing attached 
to water plants, has a disk-shaped plant body and also presents 
some new features in connection with its reproduction. Like 
Oedogonium it reproduces by zoéspores and sexually by oéspores. 
One of the new features is 
the development of a case 
around the odspore by the 
adjacent cells. This fea- 
ture suggests a close rela- 
tionship of this form to the 
higher Algae, where the 
formation of a case around 
the immediate product of 
the odspore is a prevalent 
feature. The second new 
feature is that the odspore 
upon germination develops Fic. 269. — Coleochaete scutata. <A, the 
neither a plant nor z0- plate-like plant body with two oégonia 
developed (x 25); B, thick-walled odspore 
ospores, but a structure surrounded by vegetative cells (much en- 
consisting of several cells larged); C,amuch enlarged section through 
each of which develops a the odspore and its jacket of sterile cells, 
zodspore from which a new showing the multicellular body produced 
5 by the odspore, each cell of which pro- 
plant SLIBEE: Thus between duces a zoéspore. Redrawn from Wolle, 
fertilization and the de- Atkinson, and Altmanns. 
velopment of new plants, 
there is introduced a new structural stage and one that is char- 
acteristic of higher plants. These new features with others have 
led to the theory that the higher plants have evolved from Algae 
of the type of Coleochaete. 
In having multicellular plant bodies and more advanced 
methods of reproduction, the Confervales, as a group, show 
advancement over the: preceding groups. The plant body is a 
simple filament, branched filament, or a disk-shaped structure. 
Sexual reproduction, which is isogamous in the lower forms, 
advances to heterogamy where the two kinds of gametes occur in 
