270 
PHYSIOLOGY: A. G. MAYER 
THE NATURE OF NERVE CONDUCTION IN CASSIOPEA 
By Alfred Goldsborough Mayer 
DEPARTMENT OF MARINE BIOLOGY, CARNEGIE INSTITUTION OF WASHINGTON 
Presented to the Academy, March 24, 1915 
The experimental side of this research was conducted at the Marine 
Laboratory of the Carnegie Institution at Tortugas, Florida, and the 
kymograph records were studied under most advantageous surroundings 
kindly offered in Guyot Hall, Princeton University, by Profs. Edwin 
G. Conklin, Ulric Dahlgren, and Louis R. Gary. Ring-shaped strips of 
subumbrella tissue of the scyphomedusa Cassiopea xamachana were cut 
TABLE I 
COMPOSITION OF 
THE SOLUTION 
AVERAGE RATE OF 
NERVE CONDUCTION 
IN SEA WATER DI- 
LUTED WITH DIS- 
TILLED WATER 
AVERAGE RATE OF 
NERVE CONDUCTION 
IN SEA WATER DI- 
LUTED WITH 0.415 
MOLECULAR MgCh 
RATE CALCULATED 
FROM THE FORMULA 
C^= 100-0.123 x^ -^ 
WHERE IS THE 
RATE CORRESPOND- 
ING TO ANY PERCENT 
OF DILUENT, X 
Natural sea water . , 
100 
0 
100.0 
100.00 
95 . 0 volumes sea water + 5 of diluent 
100 
5 ±0.67 
97.9 ± 0.60 
98.63 
90.0 
H « 
+ 10 " 
95 
89 ± 0.825 
95.3 ± 1.23 
96.11 
85.0 
l( (C 
+ 15 " 
92 
3 ± 1.21 
91.6 ± 0.75 
92.85 
80.0 
(( n 
+ 20 " 
88 
3 ± 1.19 
88.9 ± 1.20 
89.00 
72.0 
« « 
+ 28 " 
81 
94 =t 0.48 
81.78 
70.0 
(( u 
+ 30 " 
81 
4 =t 1.49 
78.1 =t 0.74 
79.79 
64.0 
(( (I 
+ 36 " 
73 
91 =t 0.68 
73.43 
60.0 
(( ({ 
+ 40 " 
71 
1 =ti.29 
67.2 ± 0.65 
68.88 
56.0 
<( « 
-f 44 " 
64 
55 ± 1.26 
64.10 
50.0 
+ 50 " 
56 
31 =±= 1.62 
55.4 =t 0.76 
56.50 
33.3 
+ 66.7 " 
29 
0 ± 1 
33.05 
SO as to remove the marginal sense organs, thus paralyzing the ring. 
Then a contraction wave was entrapped in the circuit, and the ring was 
placed in sea water diluted either with distilled water, or with 0.415 
molecular magnesium chloride. The decline in rate was almost identi- 
cal in similar concentrations of both these solutions although the mag- 
nesium appears to be slightly more depressant than the distilled water. 
Experiments made in 1913 showed that the decline in rate of nerve 
conduction is the same in sea water diluted with 0.9 molecular dextrose 
as in sea water diluted with distilled water, and thus it is evident that 
down to 50% concentration the decline in rate is due solely to the change 
in concentration of the cations sodium, calcium and potassium, and not 
to the reduced osmotic pressure, or to magnesium. 
