Nov., 1921] 
RABER — ■ PERMEABILITY 
Percentage 
Probable Error of the Mean Ex 
Time in 
of Original 
pressed as Percentage of the 
Minutes 
Resistance 
Mean (Three Experiments) 
2 
lOI 
0% 
5 
102 
I 
10 
92 
I 
20 
75 
6 
40 
51 
8 
60 
47 
II 
80 
46 
II 
It is seen that there is a slight rise of resistance which is quickly followed 
by a fall. That the rise is no greater may be due to the facts that (i) the 
chromium ion used carries only two charges, and (2) the dilution with the 
sodium chloride would also tend to cause an immediate fall in resistance. 
MIN — I ^ p- • 
40 80 
Fig. I. A. Effect of 50 percent CrCl20.6i M plus about 50 percent NaCl 0.52 M upon the 
permeability of Laminaria Agardhii Kjellm. Ordinates indicate percentage of the original 
resistance (considered as 100 percent) in sea water of the same conductivity as the solution 
tested. Abscissae represent time in minutes of the tissue in the solution. B. Effect of a 
solution of 50 percent Na2Cr04 0.22 M and 50 percent NaCl 0.52 M with enough chromic 
acid added to produce the same pH as in A (pH 4.5). 
