PERMEABILITY BY THE METHOD OF TISSUE TENSION 567 
Results 
It was found that in all the solutions the rate of recovery decreased 
rapidly during the first fifteen or twenty minutes, and that all the 
experiments, with the exception of those with the sea water — calcium 
chloride solution, gave data which were quite erratic during that 
period. An examination of the curve (Fig. 2) representing the rate 
of penetration of this mixed solution will show that the points, plotted 
from four experiments, fall very uniformly on a smooth curve which 
shows a rapid decrease in the rate of recovery during the first twenty- 
five minutes, after which the rate remains nearly constant. This 
decrease in the rate of recovery represents the effect of some factor 
whose nature has yet to be determined, and which is common to all 
the salts used. In view of the presence of this factor and of the erratic 
behavior of the tissue during the first one or two recoveries in solutions 
other than the sea water-calcium chloride mixture, it seems best, for 
the present, to disregard the first twenty minutes of these experiments. 
Table i 
Time Required for Successive Recoveries, Taraxacum 
Rations 
Solution 
Concen- 
tration 
Increase 
of Con- 
centration 
Minutes 
in Solu- 
tion Be- 
fore 1st 
R 
ecovery Time 
Minutes 
Recov- 
ery 
ISt 
2nd 
3d 
4th 
5th 
6th 
7th 
Balanced 
Sea water 
and CaCl2 
Mixture 
0.235 
0.0075 
9 
10 
10 
13 
13 
13 
4 
4 
2.5 
10.5 
8 
6.5 
13 
16 
5-5 
24 
21.5 
23.5 
25 
21 
15-5 
21 
22 
26 
25 
Univalent 
NaCl 
KNO3 
NH4CL 
0.22 
0.21 
0.23 
0.0075 
0.0075 
0.0075 
10 
9 
6 
6.5 
6.5 
3 
9.5 
9.0 
5 
5.0 
7.5 
II 
10 
9.0 
8 
10.5 
I I.O 
13 
lO.O 
13.0 
Bivalent 
CaCl2 
MgCl2 
0.165 
0.15 
0.0041 
0.0041 
14 
13 
24 
9.5 
51 
15 
83 
22 
34 
Trivalent 
Ce2(N03)6 
AI2CI6 
0.065 
0.047 
0.001 I 
0.001 1 
9 
13 
26 
3-5 
43 
4-5 
9-5 
45 
In the experiments with solutions of pure salts the time at which 
characteristic alteration of permeability occurred varied sufficiently 
with different peduncles and even with adjacent strips from the same 
