488 
PACIFIC SCIENCE, Vol. VII, October, 1953 
fourths of the time during each revolution 
(1:3 on-off ratio). 
Each group of experiments with interrupted 
current included several series at successively 
greater amperages. In group I, amperages of 
1, 2, 3, 4, and 5 were used. In group II, am- 
perages of 4, 5, 6, 7, and 8 were used. In 
group III, amperages of 2, 3, and 4 were used. 
At each amperage within a group, experiments 
were conducted at several frequencies of in- 
terruption. Frequencies used in group I were 
5, 10, 15, 20, and 25 interruptions per second. 
In groups II and III, frequencies of 5 , 15, and 
25 interruptions per second were used. In 
each individual experiment, five fish were used 
and two trials were made with each. The po- 
larity was changed with each trial. In all 
groups of experiments, successive tests were 
conducted until a current value was reached 
that would cause all fish to move to the posi- 
tive pole and remain there for the full 60 
seconds of each time period. If the frequency 
of current interruption proved to be a factor 
in causing the desired effect, this would be 
shown by variation in the times recorded for 
the different interruptions when both current 
and voltage remained constant. 
RESULTS 
Continuous Direct Current 
The results of tests using uninterrupted 
(continuously flowing) current are shown in 
Table 1. The fish showed no effects of the 
current flow at 1, 2, and 3 amperes. At a 
current value of 4 amperes, the fish swimming 
near the electrodes, within about 6 inches, 
would suddenly veer away as though shocked. 
This effect became noticeable at greater dis- 
tances from the electrode as the current was 
increased. At 7 amperes some fish were more 
strongly shocked in the immediate vicinity 
of the poles, but reactions were entirely eva- 
sive. The fish would swim toward one end of 
the tank; upon nearing the pole and receiving 
a shock they would turn and swim rapidly 
toward the opposite end, where the experience 
would be repeated. 
At a current value of 9 amperes the fish 
entering the area near the positive pole would 
show the typical electronarcotic effect, in- 
cluding cramped, slow movements and slow- 
ing of opercular action, which resulted in 
respiratory difficulties. If the fish were at right 
angles to the lines of force between the elec- 
trodes, the body would be bent with the head 
and tail pointing toward the positive elec- 
trode. However, the electrical field was still 
not powerful enough to hold the fish and they 
were able to escape this influence, avoid the 
vicinity of the pole, and swim to an area in 
the tank where they were affected least. 
At current values above 10 amperes practi- 
cally all fish started swimming toward the 
positive pole when the center barriers were 
removed but were repulsed rather than held 
by the increasing effects as they neared the 
positive pole. The result was that, they re- 
mained either in a low-current density area 
at the bottom of the tank near the pole bar- 
riers, or near the center of the tank away from 
both poles. Their swimming movements were 
slow and unnatural. The dorsal fin was stiffly 
elevated. 
At a current value of 14 amperes all fish 
swam toward the positive pole until the bar- 
rier was reached. Many tried to force their 
way through the protective net in their at- 
tempts to get nearer the electrode. Soon after 
reaching the net barrier the electronarcotic 
effect became evident. The fish could not 
TABLE 1 
Mean Time (in Seconds for 5 Fish, 2 Trials Each) 
Spent in the Positive Section of the Tank 
Using Uninterrupted Direct Current 
AMPERES 
MEAN 
TIME 
AMPERES 
MEAN 
TIME 
1 
33.9 
8 
36.9 
2 
27.9 
9 
19.7 
3 
34.9 
10 
38.1 
4 
26.9 
11 
30.2 
5 
30.9 
12 
41.5 
6 
38.2 
13 
46.2 
7 
32.5 
14 
60.0 
