ALG 113 
often more abundant, a single branch from the main body 
bears several lateral odgonia and a terminal coiled anther- 
idium (Fig. 102, B). 
The two important facts illustrated by Vaucheria are 
the ccenocytic body and the development of special cells to 
act as sex organs. 
Fic. 103.—Spirogyra: one complete cell, showing the spiral, band-like chloroplasts, 
with embedded pyrenoids, and a nucleus (near the center) swung by radiating 
strands of cytoplasm. 
69. Spirogyra.— 
This is one of the most 
common of the pond 
scums, occurring in 
slippery and often 
frothy masses of deli- 
cate filaments floating 
in still water or about 
springs. The filaments 
are simple, and are not 
anchored by a special 
basal cell. 
The cells contain re- 
markable chloroplasts, 
which are bands pass- 
ing spirally about with- 
in the cell-wall (Figs. 
103 and 104). These 
bands may be solitary 
ral in a cell and Fria. 104.—Spirogyra: A-C, various stages in the 
OE eee eee a development of sexual tubes; D, a completed 
form very striking and __oaspore, 
