of their bodies are huge. 
illustrate the essential features of the group. 
ALG AL 121 
Ectocarpus may be used to 
Its body is 
filamentous (Fig. 113), suggesting the body of some of the 
Conferva forms among the green Alge. Certain 
cells of the filament (Fig. 113, :1), or the end cells 
of special short branches, become enlarged and 
produce numerous swimming spores. The swim- 
ming spores of brown Alge are peculiar in usu- 
ally bearing the two cilia on one side of the body 
rather than at one end, and hence 
they are described as laterally bicili- 
ate (Fig. 115, @). 
The cell that produces swimming 
spores was sometimes spoken of 
among the green Alge as a mother- 
cell, but a mother-cell may not al- 
ways produce — spores. 
Hence it is well to use 
a term that implies the 
product of the mother- 
cell, and in this case 
the term is sporangium 
(spore-case). A sporan- 
gium, therefore, is an or- 
gan that produces spores; 
and among the Alge de- 
scribed thus far it con- 
sists of one cell. 
In addition to the one- 
celled sporangia, other 
organs in similar posi- 
tions may occur; but 
they differ from the spo- 
Fic. 113.—ctocarpus; a filamentous, branch- 
ing form: A, filament bearing one-celled 
sporangia (s); B, filament bearing many- 
celled gametangia (gq). 
rangia in being many-celled (Fig. 113, B). In each cell 
usually one body is formed, which when discharged is seen 
