no THEORETICAL AND GENERAL 



to the lines of streaming, but neither at make nor break could he observe 

 any change in the velocity of streaming. The negative results were simply 

 due to the fact that the induced currents were too weak and of too short 

 duration to produce any perceptible effect, but they led Becquerel to 

 conclude that the electromotive mechanism must be of very special 

 character. 



Velten 1 was able in dead cells, by using strong constant currents, 

 to cause more or less regular streaming motion of small particles of 

 disorganized protoplasm around the cell, and the direction of movement 

 was reversed on reversing the current. Bearing in mind the magnetic 



FIG. 13. Diagram of half of young Chara cell 

 with locally applied dye. 



FIG. 14. Sectional diagram of 

 electro -magnetic streaming. The 

 small arrows show the direction of the 

 electrical current and the large ones 

 the movement of the mercury. 



properties ' of the cellulose membrane, it seems very probable that this 

 is an electro-magnetic phenomenon, but in any case no such reversal of 

 the direction of streaming can be produced in living cells by the direct 

 action of electrical currents. It is true that as the result of the injury 

 and death of neighbouring cells the direction of streaming may after 

 a period of quiescence be opposed to the previous one ; but this is an 

 exceedingly rare phenomenon, and is probably the result of some com- 

 plicated secondary reaction. 



That weak electrical currents continually circulate in living plant- 

 cells is certain, for at the outer and inner surfaces of the protoplasm, 

 dissimilar solids wetted by dissimilar saline solutions are in contact, and 



1 Bot. Ztg., 1872, p. 147; Flora, 1873, p. 82. 



