OF THE GALVANIC CURRENT OH THE MOTOR NERVES OF MAN. 
973 
Induction pole. 
Distance of coil. 
Number of cells of 
polarising current. 
F+ 
113 
113 
0 
G+ 
117 
120 
10 
yy 
135 
140 
20 
yy 
F- 
117 
115 
0 
G- 
yy 
131 
122 
10 
y> 
>5 
151 
155 
20 
yy 
F+ 
ns 
113 
0 
G- 
» 
111 
116 
10 
JJ 
112 
112 
20 
a 
F- 
118 
118 
0 
G+ 
108 
no 
10 
yy 
yy 
103 
104 
20 
yy 
These numbers agree with the conclusions already obtained, but this method is less 
satisfactory than the graphic method; the determination of the minimum F-J-G— is 
especially variable, as indeed might have been expected from our previous results. 
D, Proof of the physiological nature of the interference id hen faradic and galvanic 
currents in one circuit are opposed in direction. 
It has been shown by one of us' : ' that the latent time of the break contraction on 
* Man far exceeds that of the make contraction. That the length of this period 
depends on a persistence of anelectrotonus after its galvanic provocative has ceased 
was proved by showing that the recovery of a faradic tetanus, interfered with by 
anodal polarisation for a given time, does not occur within a period equivalent to a 
make latency, but is delayed for a period equivalent to a break latency. The exist¬ 
ence of this period of delay is proof of physiological versus physical interference. 
From this datum it can be shown that the diminution of effect when the two currents 
are opposed is always anelectrotonic, whether the combined exploring pole be faradic 
kathode with galvanic anode or faradic anode with galvanic kathode, for in either case 
the period of persistence of anelectrotonus is observed. 
The following experiment constitutes the easiest demonstration of electrotonus on 
Man; it is an old experiment, but has not hitherto received a physiological interpreta¬ 
tion :— 
Holding in both hands the poles of a secondary coil with vibrating interrupter, so 
that both arms are tetanised, it may be observed with suitable distance of coil and 
* A. Waller, in an oral communication to the Physiological Society of London, November, 1881. 
(Arch, de Physiologie, Avril, 1882.) 
