1915] OSTERHOUT—PERMEABILITY 249 
CaCl, were added to each 1000 cc. of sea water. Owing'to the fact 
that the rise in resistance took place more slowly? than when 
lanthanum was used, the experiment was performed twice on each 
of the five successive days. On the sixth day the material was in 
as good condition as the control and had the same resistance. 
900 OHMS DAY1 DAY 2 
ee 
Fic. 3.—Alterations of permeability shown by curves of the electrical resistance of 
Laminaria saccharina in sea a water, and in 1ooo cc. sea water+2.6 gms. 
(=0.01M); the same lot of material was exposed four times daily on five successive 
days to the action of ro00 cc. sea water+La,(NO;)6; unbroken part of curve, resistance 
in sea water+La.(NO;)6; dotted part of curve, resistance in sea water; lower hori- 
zontal dotted line, control in sea water. 
It is evident, therefore, that the permeability may be greatly 
decreased and then restored to the normal several times on five 
Successive days without any trace of injury. Further experiments 
Showed that the permeability may be alternately increased and 
decreased twice daily for five days without injury. The amount 
of increase and of decrease was about the same as in the experi- 
ments just described. 
* If in place of solid CaCl, a strong solution is added, the rise is more rapid and 
teaches a higher figure. r 
