318 BOTANICAL GAZETTE [APRIL 
=0.00133 mho. After 15 minutes in CaCl, the net resistance was 
1490— 250= 1240 ohms, and the net conductance 1+1240= 0.00081 
mho. We may regard the permeability as equal to the con- 
ductivity, or, in this case, for convenience, 
as equal to the conductance. The decrease 
in permeability was therefore 0.00133— 
0.00081 = 0.00052 mho or 39.1 per cent. 
1500 OHMS 
TABLE I 
ELECTRICAL RESISTANCE OF Laminaria saccharina 
1300, 
Time in hours | In CaCh 0.278 M In sea water 
_o- 1000 970 
1100 4 1490 970 
if 5 1490 970° 
I 1490 97° 
23 Q50 979 
‘ 4 650 97° 
All readings were taken at 15° C. 
900 
: The characteristic effects of CaCl, are 
therefore a very rapid rise followed after an 
interval by a fairly rapid fall of resistance. 
It seems probable that these effects result 
from two processes which go on simultane- 
ously and represent different reactions, one 
of which has a much greater velocity than 
ry the other. In this way the period of station- 
1 2 HOURS ary resistance (represented by the flattened 
pasa Tol es top of the curve) would be accounted for. 
Laminaria saccharina in LHe fall in resistance is much slower than 
CaCl, 0.278M (unbroken that caused by monovalent kations and 13s, 
line) and of a control in jn the opinion of the writer, quite different 
sea water (dotted line). from tt 
Similar results were obtained with BaCl, and SrCl.. 
The behavior of material in a solution of MgCl., about 0.28 M, 
having the same conductivity as sea water, is shown in table I 
and fig. 2. The rise in resistance is not nearly as great as in CaCl; 
the fall in resistance begins much sooner and proceeds much more 
rapidly. The top of the curve is not flattened. | * 
