ON THE DECREASE OF PERMEABILITY DUE TO 
CERTAIN BIVALENT KATIONS 
We-k Ve OSTERR OUT 
(WITH ELEVEN FIGURES) 
It has been shown" that while NaCl and many other salts of 
monovalent metals increase the permeability of protoplasm, CaCl. 
has the opposite effect. This effect of CaCl, is not permanent; 
if the exposure be sufficiently prolonged, it will be found that it 
gradually passes away and is followed by an increase of permea- 
bility. The question arises, do other bivalent kations behave like 
calcium ? 
The method employed in this investigation was to make de- 
terminations of the electrical resistance of living tissues of Laminaria 
Saccharina in the manner described in a previous paper.t Such 
determinations afford an accurate measure of the permeability of 
the protoplasm. 
The following experiment? will illustrate the effects of CaCl. 
The resistance of a cylinder of tissue in sea water at 18°C. was 
found to be tooo ohms. It was transferred to CaCl, 0.278M, 
which had the same conductivity as the sea water. After 15 
minutes the resistance in CaCl, at 18° was found to be 1490 ohms. 
After 30 minutes more the resistance was still 1490 ohms. Another 
reading taken 105 minutes later showed the resistance to be g50 
ohms; 75 minutes later it was 650 ohms. During this time the 
control in sea water had not altered its resistance. The results 
are shown in table I and fig. 1. 
The resistance at the beginning of the experiment was 1000 
ohms; subtracting from this the resistance of the apparatus (250 
ohms) gives the net resistance or the actual resistance of the tissue, 
Which is to0o— 250= 750 ohms. The net conductance was 1+750 
* Science N.S. 35:112. I9QI2. 
* The chemicals used were the best obtainable and in nearly all cases were Kahl- 
baum’s. The solutions unless otherwise stated were neutral to litmus. This is im- 
portant, for it has been shown in a previous paper acid may cause a rise in resistance. 
S07 8 {Botanical Gazette, vol. 59 
