PHYSIOLOGY OF THE NERVOUS SYSTEM. 
1. That there is invariably an accumulation 
of vesicular matter around the points of im- 
plantation of nerves in the centres, as already 
referred to. This is true of all nerves in 
the vertebrata and the higher invertebrata, 
and we know of no reason to doubt it in the 
lower invertebrata. 2. The quantity of the vesi- 
cular matter around the point of implantation 
of a nerve is in the direct ratio of its size and 
of the activity of its function. Under par- 
ticular cireumstances the quantity of vesicular 
matter becomes so large as to cause a special 
ganglionic enlargement of the portion of the 
centre in which the nerve or nerves may he 
implanted. The cervical and lumbar enlarge- 
ments of the spinal cord are due to this 
cause: the gangliform swellings on the upper 
a of the spinal cord in the gurnard (érigla 
lyra) are connected with the exalted func- 
tions of the nerves of touch distributed to the 
feelers, and contain a large quantity of vesi- 
cular matter. A remarkable instance of the 
developement of vesicular nervous matter under 
similar circumstances is to be found in the 
electric lobes of the Torpedo, in which are im- 
planted the nerves distributed to the electrical 
organ. These lobes are of very considerable 
size, much exceeding that of any other part of 
the brain, and they contain vesicular matter in 
large quantity. The nerves implanted in them 
are of great size.* 
Such facts as those cited in the preceding 
paragraph denote clearly that the developement 
of the nervous force is to a certain extent con- 
nected with the vesicular nervous matter, and to 
such a degree as to justify the opinion that this 
element of the nervous centres may be viewed 
as the dynamic matter, the originator of the 
force. At the same time it must be borne in 
mind that this form of nervous matter never 
occurs alone, and that probably the union of 
the two is necessary for the developement of 
nervous power. Just as the union of two 
metals in the galvanic battery is necessary for 
the developement of the current, while one of 
them, that, namely, which possesses the greatest 
affinity for the fluid interposed between them, 
seems to originate the current, and is on that 
account called the generating plate, whilst the 
other is called the conducting plate. 
Of the nature of the nervous force.—All 
that we have said respecting the mode of deve- 
lopement and the laws of the nervous force 
denotes its polar character. 
We can no more detect by our senses any 
physical change in the piece of soft iron which 
is rendered magnetic by the galvanic current, 
than we can discover a change in the particles 
of a nerve stimulated to action by the same 
current. That both the iron and the nervous 
matter are thrown into an analogous state by 
the same agent seems highly probable. In the 
case of the iron the indication of the assump- 
tion and of the maintenance of the polar state 
is afforded by its power of attracting particles 
of iron; while in a muscular nerve the assump- 
tion and maintenance of the polar state are 
* Savi, Etudes Anat. sur le Systéme Nerveux et 
sur ’Organe Electrique de la Torpille. 
720P 
shown by the active contraction of certain mus- 
cles, or a more tonic state of passive contrac- 
tion. While the current is passing through a 
motor nerve there is no active contraction of 
the muscles; but that these organs are in a 
more excited state than the ordinary one of 
passive contraction seems evident enough, from 
the readiness with which they assume a tetanic 
condition upon the cessation of the passage 
of an inverse current which had been allowed 
to pass through their nerves for some time. 
And the fact demonstrated by Marianini and 
Matteucci, that the passage of a continuous 
current through a nerve will after a time exhaust 
its excitability, although not so quickly as a 
current frequently interrupted, denotes that the 
nerve is in an excited state during the actual 
passage of the galvanic current. 
Is the nervous force electricity ?—There is 
so much resemblance, as regards their mode 
of developement and propagation, between 
the nervous force and electricity, that many 
physiologists have been led to regard these 
forces as identical. The nervous force, how- 
ever, presents striking points of difference 
from electricity, which render it highly impro- 
bable that it is identical with that force, and 
which show that if it be so it must be an 
electricity of extremely low tension. 
1. The ordinary tests for electricity fail to 
detect the existence of a galvanic current in the 
nerves, whether during their quiescent or their 
active state. The most delicate galvanometers 
have been employed for this purpose, in vain, 
by Prevost and Dumas, who were themselves 
advocates of the electrical theory of nervous 
action, by Person, by Miiller, by Matteucci, 
and by myself. Person connected the wires of 
a galvanometer with the surfaces of the spinal 
cord in kittens and rabbits, in which spasmodic 
action of the muscles had been excited by the 
influence of nux vomica, and was unable to 
discover any evidence of electrical action. It 
had been affirmed that needles introduced into 
the nerves or muscles of living animals became 
magnetic during nervous and muscular action, 
so as to attract iron filings, but neither Miiller 
nor Matteucci has succeeded in obtaining such 
a result from their experiments. Matteucci 
took the precaution of employing astatic needles 
for the purpose, but could detect no signs of 
magnetization. He also introduced the pre- 
pared limbs of a frog into the interior of a 
spiral covered on its inside with varnish; the ~ 
extremities of this spiral were united to those 
of another smaller spiral, into which he intro- 
duced a wire of soft iron. The nerves of the 
frog were irritated to excite muscular action, 
and at the same time Matteucci sought to 
ascertain if an induced current would traverse 
the spirals and magnetize the wire, but to no 
purpose. 
2. Were it to be admitted that the nervous 
force and electricity were identical, it cannot 
be doubted that the provision made for propa- 
gating the latter force in the nerves is very 
Inadequate. The nerves are very imperfect 
conductors of electricity; Matteucci assigns to 
them a conducting power four times less than 
that of muscle; Weber states that they are very 
