720q 
inferior to the metals as conductors. And 
from experiments made on this subject in 1845 
by Dr. Miller, Mr. Bowman, and myself, we 
were led to conclude that nerve was infinitely a 
worse conductor than copper. ‘The provision 
for insulation, however perfect for the nervous 
force, seems most insufficient for electricity, 
unless, perhaps, for a current of very feeble 
intensity. Yet we know that the nerve fibres 
convey the mandates of the will with the nicest 
precision to the muscles, and propagate the 
effects of physical stimuli applied to the peri- 
hery with the greatest exactness to the centre. 
his could scarcely be if the force so propagated 
were an imperfectly insulated electric current, 
for jt is evident that in such a bundle of fibres 
as a nervous trunk disturbances would conti- 
nually be taking place, from the secondary 
currents induced in neighbouring fibres by the 
electricity passing through those in action. 
3. The nrm application of a ligature to a 
nerve stops the propagation of the nervous 
power along that nerve below the point of 
application; the passage of electricity, how- 
ever, is not interrupted by these means. The 
nervous trunk, indeed, is as good a conductor 
of electricity after the application of the ligature 
as before it, provided it do not become dry at 
the point of ligature. 
4. If a small piece be cut out of the trunk 
of a nerve, and its place supplied by an electric 
conductor, electricity will still pass along the 
nerve and along the conductor ; but the nervous 
force, excited by a stimulus applied above the 
section, will not be propagated through the 
conductor to the parts below. 
5. The existence of an organ in certain ani- 
mals capable of generating electricity is un- 
favourable to the electric nature of the nervous 
force. The best examples of this organ are 
found in the Torpedo and the Gymnotus; and 
experiment has placed it beyond doubt that the 
organ generates electricity, which is capable of 
giving a shock similar to that from a Leyden 
jar; which developes a spark during the dis- 
charge, and can effect electrolysis; by which, 
likewise, the galvanometer may be disturbed, 
and needles rendered magnetic. 
The electrical organs have no resemblance, 
in point of structure, to nerves; they, however, 
present a remarkable analogy in that respect, as 
well as in their physiological action, to the 
striped variety of muscles. They are composed 
of a number of prisms, each of which consists 
of a membrane closed at both extremities, and 
containing a soft albuminous substance, but 
subdivided by transverse very delicate septa 
into a multitude of small compartments. The 
bloodvessels and nerves are distributed upon 
the enclosing membrane and upon the septa, 
but do not penetrate the albuminous material. 
On these septa, according to Savi, the nerves 
form a network, in which the disposition of 
their terminal fibres differs from that in muscle 
in there being a true anastomosis or fusion of 
the primitive tubules. The analogy of the struc- 
ture of the electrical prisms with that of mus- 
cular fibres is sufficiently obvious, the latter 
* See ELECTRICITY, ANIMAL. 
PHYSIOLOGY OF THE NERVOUS SYSTEM. 
being prismatic columns of fibrine, enclosed by 
a membrane, the sarcolemma, and separable 
into dises, the nerves and vessels being distri- 
buted upon the sarcolemma, and not penetrating — 
the contained sarcous elements. In both these 
textures the anatomical disposition has evident 
resemblance to the artificial arrangements for 
generating electricity, and accordingly in one 
(the electric organ) true electricity is generated ; 
in the other, as we shall see further on, either 
electricity, or a force in close relation to elec- 
tricity, is developed. In both cases the genera- 
uon of the force is independent of the nervous 
system ; its exercise and application, however, 
are under the influence of that system. "4 
The arrangement of the nerves and nerve 
centres is essentially different from that of 
muscle or of the electric organ, and so far 
would suggest a decided difference in the 
racter of the force which they can develope from 
that produced by the latter textures. ; 
6. A comparison of the muscular with the 
nervous force throws somelight on the nature of 
the latter, and upon its true relation to elec 
tricity. me 
Matteucci has established beyond a sh 
of doubt that electricity of teeble tension is gene= 
rated in the ordinary nutrition of the muse 
of all animals, and by a particular arrange 
this may be made to assume the current 
passing from the interior to the exterior of 
muscle. The source of this electricity is” 
doubt to be found in the chemical action 
accompanies the nutrition of the museu 
tissue, “ gp gots that which takes place. 
the contact of the arterial blood with’ 
muscular fibre.”* The intensity of this ew 
rent increases in proportion to the activity 
muscular nutrition, and in proportion to 
rank the animals occupy in the scale of beings 
It requires a particular artificial arrangement t 
accumulate the electricity in such a manner as 
that it shall affect the galvanometer; “ durin 
life the two electric states evolved in the mu 
cle neutralize each other at the same poimts 
from which they are evolved;” but in 
arrangement of a muscular pile as devised b 
Matteucci, “a portion of this electricity is p 
in circulation just as it would be ina pilee 
posed of acid and alkali, separated from 
other by a simply conducting body.” 
During the active contraction of a muse 
however, a force is developed which has | 
semblance to electricity, and in his early 
ments was regarded in that light by M 
This power is capable of affecting the t 
the frog in the same manner as electricity. 
following experiment displays this :— 
lower extremity ofa frog and skin it; di 
the sciatic nerve from among.the muscles” 
the posterior part of the thigh, and then se 
rate the thigh by cutting it across just ab 
the knee-joint, leaving the nerve connect 
with the knee and leg; this a4 ion is | 
galvanoscopic frog, so called by Matteucci fo 
the readiness with which it indicates an ele 
tric current; next prepare the lower 
mities of a frog according to Galvani’s m 
‘ 
* Phil. Trans. 1845, p. 294. 
