322 BOTANICAL GAZETTE [APRIL 
protoplasm and not in the intercellular substance is clearly shown 
by the fact that as soon as the protoplasm is killed, no rise is pro- 
duced on adding solid CaCl,. This is true when the means of 
killing is such as to produce no change in the intercellular sub- 
stance, e.g., by slight reduction of the water content by partial 
drying, by allowing the material to stand in the laboratory until 
dead, or by raising the temperature to 45°C. 
If the rise in resistance were not due to a change in permeability, 
it could be explained only as the result of a decrease in the size of 
1100 OHMS 
\ 
900) ae en 
‘ t i 
5 10 20 30 HOURS 
Fic. 5.—Curve of electrical resistance of Laminaria saccharina in sea water 
1000 cc. +(MnSO,+7H20) 1.39 gm.=(o.005 M) (unbroken line), and of a control 
in sea water (dotted line). 
the spaces between the cells. Both macroscopic and microscopic 
measurements show most conclusively that this does not occur. 
The contrary effect would be produced by the addition of salts in 
solid form, for they would tend to produce plasmolysis and thereby 
to increase the space between the cells. 
In order to test further the effect of MgCl, 1o cc. of a 5 M so- 
lution were added to r1ooocc. of sea water. A reading taken 5 
minutes later showed that the resistance had fallen from 780 to 
700 ohms; it continued to fall slowly throughout the experiment. 
The writer interprets this as showing that MgCl, is not able to 
