384 
AMERICAN JOURNAL OF BOTANY 
[Vol. 8 
resistance changes as shown in figure i, C (three experiments; probable 
error less than 3 percent). It is seen that without the citrate the rise in 
resistance is much higher than with the citrate. In other words, the citrate 
has a decided tendency to keep the resistance from rising at the start. 
If the proportion of citrate in the mixture is now increased from one 
sixth to one third, results are obtained as shown in figure i, D (three experi- 
ments; probable error less than 3 percent). 
A 0.20 M solution of magnesium chloride has about the same conduc- 
tivity as the last mentioned solution, and if tissue is placed in it the results 
are as shown in figure i, E (three experiments; probable error less than 
5 percent). Here it is seen that the resistance rises slightly in the 0.20 M 
solution of magnesium chloride, but that if enough magnesium citrate is 
added the resistance does not increase, but decreases from the beginning. 
This is of interest since it shows the importance of the anion in studies on 
permeability. 
Figure i, shows the changes in resistance in a mixture composed of 
two thirds aluminum chloride 0.40 M and one third aluminum citrate 
1.09 M. This mixture has a pH of about 3 and the conductivity of a 
solution of 63 percent sea water plus 37 percent distilled water. The curve 
shows the average of two experiments (in which the probable error of the 
mean is under 3 percent of the mean). 
Figure i, G shows the resistance in a solution of pure aluminum chloride 
of the same conductivity as that represented by curve F. The number of 
experiments and the limit of probable error are also the same. The pH of 
this solution is about 4. 
Since it is known that acid produces an initial rise in resistance, it might 
be thought that the acidity of the solutions is the chief factor in the effects 
produced. If this were true, we should expect that the greater the con- 
centration of the citrate the greater would be the initial rise in resistance 
since the citrate is the more acid of the two salts, but this is just the reverse 
of what is found to be the case. 
Again it may be suggested that in mixtures of magnesium chloride and 
citrate and of aluminum chloride and citrate synergetic effects are present 
which cause especially rapid decrease in resistance. Since pronounced 
synergy has been found between the chloride and citrate of sodium (5), this 
is quite possible. The possibility of synergetic action can not be denied, 
but even if it is present it is evident that the anion has a powerful influence. 
Moreover, the experiments with magnesium sulphate (where there is no 
possibility of synergetic effects) show that bivalent cations may be pre- 
vented from causing an appreciable increase in resistance if they are used 
with bivalent anions. 
Summary 
Bivalent and trivalent cations in combination with monovalent anions 
produce an increase in the electrical resistance of Laminaria, but when 
