PROPERTIES OF VEGETABLE PROTOPLASM 3849 
filled with granules, as in their absence it is so transparent 
that it is impossible to say whether it is in motion or not. 
In the leaf of Hlodea we find a very good instance of this 
movement. Each cell contains a considerable quantity of 
water, so that the protoplasm for the main part is found as 
a layer lining the cell-wall. This layer consists of two 
parts, an outer one in which are situated the chloroplasts, 
and an inner one in which are large numbers of fine 
granules. It is this inner layer which exhibits the move- 
Fic. 149.—CELLS FROM THE -LEAF Fie. 150.—Two CxLhs FRoM A 
oF Elodea. x 300. SramMinaL Harr or Lrades- 
n, nucleus; p, protoplasm, in which cantia. x 800. 
are embedded numerous chloro- The arrows show the direction 
plasts. The arrows show the of the movement of the 
direction of the movement of the protoplasm. 
protoplasm. : 
ment, which can be seen as a streaming motion of the 
‘granules, the whole layer flowing slowly round the cell 
(fig. 149). 
In other cases, particularly in long pollen-tubes, where 
the distribution of the protoplasm is so far different that 
bands or bridles of it cross the vacuole in various directions, 
the movement has a more complicated course, streams of 
granules passing along these bridles as well as along the 
peripheral portions of the protoplasm. These two cases of 
