252 BOTANICAL GAZETTE [MARCH 
This was greater than the normal by 0.000156—0.0013=0.00026 
mho, or a gain of 20 per cent. 
The fact that protoplasm is able to endure such violent altera- 
tions of permeability throws a new light on the normal life processes 
of the cell. In the course of metabolism a great variety of sub- 
stances are produced which affect the permeability of the proto- 
plasm. Since it is clear that the permeability may be increased or 
1500 OHMS Day1 DAY 2 
1300. 
1100, | | | 
| | 
ae ry EY- ie SS 
| | | 
900 | | | 
30 60MIN 30 60 MIN 
Fic. 4.—Extreme alterations of permeability shown by curves of electrical resist- 
ance of Laminaria saccharina in CaCl, 0.278 M (unbroken line), in NaCl 0.52% 
(dotted portion of curve), and in sea water (dotted line with points); horizontal 
dotted line, control in sea water. 
decreased 30 per cent or more without rendering a return to normal 
permeability impossible, it is evident that considerable fluctuations 
in permeability may form a normal part of the life processes of the 
protoplasm. In this way the whole course of metabolism may 
be controlled, since this evidently depends on the exchange of sub- 
stances between the cell and its environment. 
