180 
On the Active Part of the Nerve Fibre, 
cylinder, while it remains in connection with its central cells during 
the life of the animal. 
If we were to take a bundle of several marine cables, and smear 
the gutta-percha investment carelessly over the cut ends of the 
copper wire cores, at a distant part of the circuit, and then transmit 
a most powerful current through the deranged wires, we should not 
find the needles acting as they did when very delicate currents were 
made to traverse an individual wire. The differences observed 
might induce some to conclude that the current by which the 
instrument was influenced in the normal state, was totally distinct 
in its nature from that much more powerful current which gave 
rise to the much greater hut irregular and unmeaning disturbances. 
This reasoning is applicable to the experiments in which strong 
electric currents have been transmitted along compound damaged 
nerve trunks. 
Fallacy of the Argument based upon the Excitability of 
Nerve Fibres. 
It has been said that the fact that nerve loses its excitability 
without losing its power of conducting electricity, is a fatal objection 
to the doctrine that the nerve current transmitted during life is of 
the nature of electricity. But many things seem to have been 
entirely overlooked by those who urge this argument with so much 
confidence. Is it not obvious that soon after death the bioplasm, 
which is instrumental during its life in maintaining an equable flow 
of nutrient fluid through the tissue adjacent to it, must cease to 
effect this important change ? Is it not certain that in consequence 
the axis cylinder of a nerve fibre must he much changed, and espe- 
cially at the peripheral distribution of the fibres where they are very 
delicate and ramify naked upon the muscular tissue ? No wonder, 
then, that the muscles fail to respond to the stimulus as before. 
This fact is attributed to the nerve having lost its “ excitability ” ; 
hut is it not more probable that the true explanation of the fact is, 
that in consequence of the change in the constitution of the nerve 
fibre, resulting from the cessation of the currents of fluid through 
it consequent upon the death of the bioplasm, it fails to conduct the 
electrical current as it did when in a state of integrity ? So far, 
therefore, from the above fact being an argument against the idea 
that nerve force is really electricity, it actually affords support to 
this view. 
The power of causing the muscles to contract when the nerve is 
irritated is lost sooner if the nerve be irritated than if it he at rest. 
It is increased by heat and decreased by cold. When the nerve is 
“ irritated,” the operation is such as would be certain to alter any 
structure so delicate as the peripheral ramifications of nerves, and 
