x1.) STONEWORTS, AND PEPPERWORTS. 167 
the Characez, or Stoneworts. They have exceedingly 
slender stems, but in spite of their slenderness and 
_ brittleness they sometimes attain the length of three 
or four feet. They are leafless, but, like Egutsetum, 
give off a whorl of branches from the nodes. The 
plant is attached to the bottom of ponds and streams 
Fic. 121. 
by slender rootlets, which are also given off from the 
nodes. The most remarkable feature of these plants 
is the structure of the stem and branches. Each inter- 
node consists of a large and long cell (axial ce//), in- 
vested by a number of spirally-arranged, smaller 
and narrower cells (cortical cells), so transparent that 
the axial cell can be seen through it. The axial cells 
are separated at the nodes by a layer of smaller (zoda/ 
cells), which is a continuation of the cortical layer. 
