130 ELEMENTS OF BOTANY. 
cell and down the other.’ A more complicated motion is the 
circulation of protoplasm, shown in cells of the jointed blue 
hairs in the flower of the common spiderwort and in the 
stinging hairs of the nettle (Fig. 103.) The thin cell wall of 
each hair is lined with a protoplasmic layer in which are seen 
many irregular, thread-like currents, marked by the move- 
ments of the granules of which the protoplasmic layer is full. 
1See Huxley and Martin, under Chara. 
