244 BOTANICAL GAZETTE [MARCH 
conductance 1+790=0.00127 mho. After treatment with NaCl 
the net resistance was 860—230=630 ohms, and the net con- 
ductance was 1+630=0.00159 mho. The increase in net conduct- 
ance, therefore, was 0.00159—0.00127=0.00032 mho, or 25.2 
per cent. The increase in the percentage of sodium ions was only 
2 per cent, while the content of chlorine ions remained unchanged. 
It is evident, therefore, that there was a great increase in per- 
meability. 
In order to see whether this increase of permeability is accom- 
panied by injury, an experiment was made in which the same piece 
of tissue was exposed to the action of NaCl several times during the 
same day. The resistance of the tissue in sea water was Toro ohms; 
after five minutes in NaCl the resistance fell to 880 ohms; the 
tissue was then placed in sea water and a reading ten minutes 
later showed that the resistance had risen to toro ohms. During 
the next 95 minutes it showed no change. It was then placed in 
NaCl for five minutes and the resistance fell to 870 ohms. It was 
replaced in sea water; a reading taken ten minutes later showed 
that it had returned to normal, where it remained for go minutes 
without change. It was then placed in NaCl for five minutes. The 
resistance fell to g00 ohms and returned to normal during the ensu- 
ing ten minutes in sea water. After 105 minutes in sea water, 
during which no change occurred, it was again exposed to NaCl for 
five minutes. The resistance fell to 870 ohms and returned again 
to normal during the following ten minutes in sea water. On the 
following day its resistance was only 30 ohms below the resistance 
of the control, which at the beginning of the experiment was 104° 
ohms. The results are presented graphically in fig. 1. 
The successful outcome of this experiment lead to an attempt 
to carry on such an experiment for several days in succession, 
giving the tissue one treatment daily with NaCl. The material 
was selected with especial care. The fronds were fairly thick, 
without reproductive organs. The experiment was made at Woods 
Hole, Mass.. in July, at which time such fronds may be easily 
obtained. The disks cut from these fronds were slightly curved, 
so that when placed in the apparatus they separated spontaneously, 
thus allowing the running sea water in which they were kept to 
