134 BOTANICAL GAZETTE [SEPTEMBER 
stage. The picture at death point has already been described 
in detail. 
If the current is continued for a longer period than is necessary | 
to produce death, all protoplasmic contents, especially the cortical 
cells of first 3-4 mm. of tip, are aggregated in a dense mass against 
the cell wall toward the positive electrode, as shown in pl. II, also 
partially shown in figs. 9 and to. 
Discussion 
Within thirty seconds after the current is applied, the resistance 
in the circuit falls considerably. The resistance, however, was 
always kept constant by means of the sliding rheostats. Coincident 
with the drop in resistance, the tiny droplets of liquid appeared on 
the surface of the root in the region of rapid elongation and above. 
This suggests increased permeability of the protoplasts and of the 
cell walls to liquids of the cell sap, and further suggests increased 
freedom of movement of particles in the sap or cytoplasm or both. 
The consequent loss of turgidity and shortening of the root sub- 
stantiate this view. 
It is most interesting to find that the greatest visible effect of 
the current is not in the region of most rapidly dividing cells, but 
slightly farther from the tip. This suggests that the protoplasm 
of these cells exists in a much more viscous state than in cells 
farther from the tip. The lack or presence of free ions would 
influence conduction of current. It is possible that free ions exist 
in increasingly greater number with the absorption of water from 
the primordial meristem to the region of greatest elongation. If 
this assumption is true, we would expect least effect of current in 
the primordial meristem, where the cytoplasm would be viscous 
and behave as a gel, and a greater effect where the cytoplasm 
became more nearly semi-fluid, and least effect where the free ions 
of the cell sap conducted the current almost altogether. This 
assumption agrees with the facts, for the least (or no) migration 
occurs in the cells with large vacuoles. 
In no preparations made could any basis be found for HarpDy’s 
(9) statement that the cytoplasm migrates to the wall, loses its 
original charge, gains one of opposite sign, and then migrates toward 
