i885-] 
Electric Organ of the Torpedo. 
733 
On examining the phenomena of polarisation presented by 
the electric organ when traversed in rapid succession by 
currents of brief duration passing alternately in the same 
direction as the animal’s own current, from the belly to the 
back (or, as Professor Du Bois Reymond calls them, homo- 
dromous currents,) and in the opposite direction (hetero- 
dromous currents, the preponderance of the former (homo- 
dromous) was found most decisive. The thought imme- 
diately suggested, of an unequal conductivity of the eleCtnc 
organ for currents of the same and of an opposite direc- 
tion, seemed to require a definite experimental investiga- 
tion! In the first place it was necessary to decide whether 
the stronger aXion of the homodromous current as observed 
was merely apparent, or really existing. 
The first observation made on the more precise observa- 
tion of this phenomenon was its very striking dependence 
on the density of the current. If the opening shocks of a 
sledge-induXion-apparatus (the primary coil being filled 
with rods of iron) were passed through the preparation 
from one skin-surface to the other, alternately in a homo- 
dromous and a heterodromous direction, the deviations of 
a galvanometer placed in the same circuit were greater with 
homodromous than with heterodromous currents. I he 
ratio of the heterodromous to the homodromous deflections 
was = ioo : 2247, if the distance of the secondary from 
the primary coil was 0 ; if this distance was 10 centimetres 
the ratio was = 100 : 105-1, whilst at a distance of 15 
centimetres the ratio became 100 : 100. From the experi- 
ments, of which the figures quoted form merely a specimen, 
it follows firstly that the phenomenon becomes perceptible 
only when the strength of the current passes a ceitain 
limit, and secondly that the irreciprocity increases with the 
strength of the current, though more slowly than the 
de itwas further established by experiment that the differ- 
ence in the strength of the currents becomes visible not 
onlv when they are passed from one polar suifaee of the 
preparations (covered with skin) to the other, but between 
any given points of the lateral surfaces of the piepaiations, 
the more strongly the more remote from each other the 
points are situate. . . , , f 
If induction currents were passed to the lateral sui faces 
of the preparations by means ct unpolansable eleXrodes, the 
heterodromous deflexions in a long layer of the organ were 
to the homodromous as 100 : 39'i; m one of medium leng 1 
as 100:45-8; and in a short distance only as roo : 78 4. 
