1915] OSTERHOUT—PERMEABILITY 247 
In order to ascertain whether this change in permeability is 
reversible, the tissue was replaced in sea water. In the course 
of an hour its resistance returned again to the original condition. 
The experiment was then repeated three times on the same lot of 
material with practically the same result; it was then allowed to 
stand over night in sea water. On the following day there was no 
1100 OHMS 
DAY1 2 3 4 5 
= ® 
~ 
ul 
10MIN 
2.—Alterations of permeability shown by curves of the electrical resistance 
of Eenumie saccharina in NaCl 0.52M (unbroken line) and in sea water (dotted 
portion of curve); upper dotted line, control in sea water. 
appearance of injury, and its resistance was the same as that of 
the control, which had remained in sea water throughout the 
experiment. The tissue was then placed in the sea water plus 
lanthanum and left until its resistance had increased 100 ohms; 
it was then put back into sea water and left until the resistance fell 
to nearly normal. This was repeated three times, and the tissue 
If the material is left in sea water plus lanthanum nitrate the increased resistance 
is maintained for a long time unaltered. 
