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. 



* See Huxley and Martin, under Chara, 



