182 



Papers frovi the Department of Marine Biology. 



and normal in sea- waters ranging from 7 to 8.65 Phj the relatively acid 

 water is made from normal sea-water treated with HCl and the alkaline 

 water from normal sea-water treated with HNaCOs, a,nd Na2C03. 



80 



90 100 110 



CONDUCTIVITY .V 



FlGURE 1. ■ 



If, however, the water is made as acid as 6.7 P„, the rate falls slightly 

 so as to be about 98, that in normal sea-water being 100; and at 6.3 Ph 

 the rate declines to 80 with greatly reduced muscular activity; but it 

 recovers in all respects almost immediately upon being replaced in 

 normal sea-water. 



At 30° C. the neutral point is about 6.8 Ph and it then appears that 

 in sea-water any excess of H* over OH' is decidedly depressant, while 

 correspondingly alkaline sea-water produces no ill effects. 



Assuming the electrical conductivity of normal sea-water of 36.24 

 0/00 sahnity and 8.22 Ph to be 100, it appears from table I and figure 1 

 that the rate of nerve-conduction augments in practically a straight line 

 as the relative electrical conductivity of the sea-water increases from 51 

 to about 108, above which the rate falls off rapidly, becoming about 77 

 in concentrated sea-water having an electrical conductivity of 152.9. 



The formula isy = 0.945.T-f 4.4 ; y is the rate of nerve-conduction, that 

 in natural sea- water being 100; x is the electrical conductivity of the 

 sea-water, that of normal sea-water being 100. 



The electrical conductivity of the sea-water was determined by 

 Kohlrausch's method, using a tunable telephone and a I.eeds and 

 Northrup revolving dnun bridge. The figures given in table I are for 

 sea-water at 30° C. 



It was found that the electrical conductivitj^ of sea-water of 36.24 

 0/00 sahnity and 8.22 P„, at 30° C. was 4.21 times that of N/10 KCl 

 at the same temperature. If, however, the sea-water be compared 



