182 



Papers from the Department of Marine Biology. 



and normal in sea-waters ranging from 7 to 8.65 P H ; the relatively acid 

 water is made from normal sea-water treated with HC1 and the alkaline 

 water from normal sea-water treated with HNaCOs, and Na 2 CO 3 . 



no 



100 



90 



u 



80 



70 



60 



\ 



120 



130 



140 



150 



50 60 70 80 90 100 Hfl 



CONDUCTIVITY X 



FlGURE 1. 



If, however, the water is made as acid as 6.7 P H , the rate falls slight ly 

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

 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 P H 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 salinity and 8.22 P H 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 is y = 0.945.T +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 Leeds and 

 Xorthrup revolving drum bridge. The figures given in table I are for 

 sea-water at 30 C. 



It was found that the electrical conductivity of sea-water of 36.24 

 0/00 salinity and 8.22 P H , at 30 C. was 4.21 times that of N/10 KC1 

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



