W. J. V. OSTERHOUT 



619 



consider 91.8 minutes in CaCl2 to be equivalent to 91.8 -i- 6 = 15.3 

 minutes in NaCl and the total exposure to be equivalent to 60.6 + 

 15.3 = 75.9 minutes in NaCl.^ The value of may then be found 

 by means of formula (4). 



X NaCl 

 o. Ca Clz 



D Sea Water 



400 



MINUTES 800 



Fig. 4. Curves showing the electrical resistance of Laminaria agardhii in NaCl 

 0.52m, in CaCU 0.278m and in sea water. Unbroken Hne, calculated values; 

 broken line, observed values. Average of ten or more experiments; probable 

 error of the mean less than 10 per cent of the mean. 



^ This mvolves the assumption that is not restored to any extent during recov- 

 ery in sea water. This assumption may not be quite correct, especially at the 

 start, but even in that case the present calculation would not be appreciably 

 altered. 



