IN THE LEAF-CELLS OF ANACHARIS ALSINASTRUM. 281 



the cell current than otherwise. When a stoppage occurs, 

 the corpuscules of the circulating layer become piled against 

 the back ot the last granule ; in some instances almost to 

 overflowing ; but the disentanglement is generally effected by 

 the tractive inlluence o^ the moving investment releasing the 

 preceding granules in succession. 



The chlorophyll granules do not appear to possess any 

 affinity for the active investment; they seem to be attached to 

 it only by simple adhesion. When a granule has been 

 impelled against an obstacle, it is sometimes thrown out from 

 the cell-wall, and, during the first instant of its rise, I have 

 seen it draw up a column, or thread, of the glutinous corpus- 

 cules. If the granule becomes quite detached, it will remain 

 stationary in its position, close to the investment, till it is 

 forced again into the line of march by the contact or motion 

 of succeeding ones. 



The investment of active corpuscules is strongly attracted 

 by the cell-wall, and the progressive activity of the one 

 appears to be dependent upon the vital condition of the other. 

 If the continuity of a portion of the surface of the cell-wall is 

 impaired, the active layer will not travel over the part thus 

 tliffering in substance. Fig. 3 represents one of the hollow^ 

 spines, or hairs, at the margin 

 of the leaf; in these the granules 

 are sometimes seen in active mo- 

 tion. When they arrive near the 

 apex, where the cell-wall is in- 

 durated, shown by a brown dis- 

 coloration, indicating a loss of 

 vitality, they are invariably car- 

 ried across the circulating layer, 

 taking a short cut over, as at b 

 in the figure. A few stray gra- 

 nules are sometimes thrown into 

 tlie dark-coloured hollow end of 

 the hair, but these are motionless. 



Although there is undoubtedly 

 a principle of attraction existing 

 between the active investment 

 and the cell-wall, yet I am led 

 to conclude that there is nothing 

 peculiar in the structure of the 

 surface of the latter to determine 

 the direction of rotation of the 

 travelling current. When a plant of tiic Anacltaris has 

 been kept in a cold, dark place for one or two days, usually 



Fiff. 3. 



d Wi 



