320 BOTANICAL GAZETTE [APRIL 
In a solution of MnCl, (about 0.317 M), having the same con- 
ductivity as sea water, the tissue shows a rapid and very decided 
rise, followed by a fall which is noticeably slower than that in 
CaCl,. The results, as shown in table ITI and fig. 3, are in marked 
contrast to those obtained with MgCl. 
TABLE II 
ELECTRICAL RESISTANCE OF Laminaria saccharina 
| 
Time in hours In MnCl 0.317 M | In sea water 
| 74° 
| aie 
joo 
All readings were taken at 18°C. 
The rise in resistance in these solutions was so great that it 
seemed to the writer that a rise might be obtained when the sub- 
stances in question were added directly to the sea water, either as 
concentrated solutions or in solid form. Accordingly rocc. of 
CaCl, 5 M were added to rooo cc. of sea water and a lot of tissue 
was placed init. The resistance rose’ from 1290 to 1390 ohms, where 
it remained stationary for a long time and then began to fall. When 
the same experiment was tried on dead tissue the resistance fell at 
once and remained stationary indefinitely. The results are shown 
in tables IV and IVa and fig. 4. The addition of solid anhydrous 
CaCl, gave a similar result, although the rise was not as great. 
TABLE IV 
ELECTRICAL RESISTANCE OF Laminaria saccharina 
sea In sea water 1000 cc. 
Time in hours +CaCh 6M toc. In sea water 
° 1290 1320 
$ 1280 1320 
3 1300 eae: 
2 1380 1320 
23 1390 eae 
I 1390 1320 
All readings were taken at 18° C. 
3 The temporary fall in resistance at the start was due to the increased conduc- 
tivity of the solution contained in the apparatus and in the intercellular substance. 
