190 © Authentic Experiments on the Phenomena of Galvanifm. [April 
the animal arc; that which is formed of 
re Galvanic inftruments. may be called 
the excitatory arc. .'The latter ufually 
confifts of more pieces than one, of which 
fome are named fiays, braces, &c. others, 
communicaters, . trom their refpective 
tfes. 
In his report of tiiefe experiments, the 
writer of it arranges his matter under 
theie fix heads: 1f. Refults ef the diffe- 
rent combinations and difpofitions of the 
parts of the azimal arc. 2d. Account of 
what has been obferved of the nature and 
the different difpofitions of the exritatory 
are, 7 3d. Circumnttances not entering into 
the ,compoiition of the Galvanic circle, 
which, neverthelelefs, by their infltence, 
wiodify, alter, or entirely prevent the 
fuccefs of the experiments. 4. Means 
propofed for varying, diminifhing, or 
reftoring the fenlidility to Galvanafn. 
sth. Attempts to compare the phzeno- 
miena of Galvanifm with thofe of elec- 
fricity. 6th. Additional experiments, 
performed by M. HumMsoupr, in the 
prefence of the membets of the commit- 
tee; which have a referenec-to feveral of 
the proofs fated in the foregoing articles. 
I. Yo.the: number of twenty expert- 
ments were made on the ANIMAL ARC. 
The firft leven of theie were dire@ed to 
aicertain the relations between the nerves 
and thofe mufcles, over which they are 
aiftributed. In the faft thirteen, the 
nerves were cut afunder, or fubieéted 
to ligatures; the fection or ligature be- 
ing always between the extremities of 
fhe arc..’ Nerves. taken from different 
animals, or from different parts of the 
fame animal, and joined in one 
arc, were 
ubjects of thele experimen 
the folitary nerve, an 
mufele, included between the 
the excitatory arc. “here were inter- 
ofed too, in the courfe of thefe experi- 
uts, portions of nerves, and of mulcles, 
inét from thofe parts. And in fome 
f the experiments, the animal was with- 
wut the tkin and the epidermis. 
The following are the inferences which 
amons the 
rm 
L 
a 
Fy, 
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(ese \s3 a SH) 
& 
have been deduced from thefe experi- 
ments. 
1, Lhe animal are may confift either 
a nerves and muicles together, or of 
: without mufcles. 
2. Nerves are, therefore, the effential 
of the anpmal arc; for #1 
1ore or lels interfected by the 
$3 and are, confequently, in party 
hervous organ. 
e parts of the animal are mut 
a 
BS 
tween the divided. parts. 
be either mutually continuous, or at leaf 
contiguous to one another. But even 
contiguity is fufiicient to enable the Gal-. 
vanic phenomena to take place. 
4. The feGiion or ligature of a nerve 
interrupts not the Galvanic phenomena, 
if the parts which are cut afunder, or 
bound up, ftill remain in clofe contiguity. 
to one another, 
5. No diverfity of the parts forming. 
the animal arc, though thefe be taken 
from different parts of the fame animal, 
or even from different animals, will have. 
power to impair its Galvanie fufceptibi- 
lity, provided oniy, that thele parts be 
{ili mutually contiguous. 
6. It the zztegrity or Galvanic fufcep- 
tibility of the animal are be fulpended by 
the feparation of any of its parts, to 
fome diftance from one another; it may 
be reftored by the interpofition of fome 
fubfances, not ef an animal nature, be- 
Metallic fub- 
ftances are in particular fit for this ufe, 
But the mutual contiguity of all the fub- 
ftances entering into the compofition of 
the arc, muft ever be carefully preferved. 
7. Vhe mufcular organs which indi-. 
cate, by contraétion, the prefence of the 
Galvanic influence, are always thofe in 
which the nerves of acomplete animal are 
have their ultimate termination. 
From this it follows, that the mufcles 
affected by Galvanifm are always thofe 
correfponding to that extremity of the 
arc which is the moft remote from the 
origin of the nerves of which it is com- 
poled. 
8. When all the nerves of the animal 
arc originate towards one of its extre- 
mities, then only thofe mufcles which 
correfpond with the oppofite extremity 
are futceptible of Galvanit convulfions. 
9. When an animal are confifts of more 
than one fyftem of different nerves, which 
have ajl their origin about the middle of 
the arc, then will the mufcles of thefe 
feveral fyftems of nerves be moved alike 
at both the extremities of the arc. 
10. It feems likewile to appear, from 
a variety of thefe experiments, that the 
‘opinion of thofe is inadmiffible, whe 
alcribe the phenomena of Galvanifm to 
the concurrence of two different and re- 
ciprocaily ‘corre{ponding influences, one 
bilonging to the nerve, the other to the 
mulcle, and who compare the relations 
between the nerve and the mvfcle, in thefe 
pheenorncna, to thole between the interior 
and the exterior costing of the Leyden 
phial, ; 
1x, It appears, laftly, that the cover- 
ing. 
