896 
above facts we believe that the cesophageal 
filaments are chiefly incident and motor, and a 
few of them only are sensiferous. 
Cardiac branches—We have in a former 
part of this work (article Hearr) had occasion 
to state that several celebrated physiologists 
have failed in exciting the muscular contractions 
of the heart by irritation of the trunk of the 
vagus before it gives off its cardiac branches, or 
of these cardiac branches themselves. We have 
very frequently repeated this experiment upon 
animals immediately after death, and we have not 
been able to satisfy ourselves that galvanic and 
mechanical excitation of these nerves has any 
effect in renewing or increasing the contractions of 
the heart. No doubt we have not unfrequently 
seen the contractions of the heart become more 
frequent and vigorous during the performance 
of this experiment ; but as similar changes in 
the strength and rapidity of its contractions are 
occasionally observed in an animal after death 
when no artificial excitant has been applied to 
these nerves, and from causes which cannot at 
present be explained, we did not think ourselves 
entitled to attribute these changes in the heart’s 
action to the excitation of the nerves. Valen- 
tin* has stated that he has produced muscular 
contractions in the heart in different animals -by 
irritation of the trunk of the vagus. He also 
statest that similar contractions of the heart 
were produced by excitation of the spinal ac- 
cessory and of the three superior (sometimes 
also of the fourth) cervical nerves, and he main- 
tains that the motor portion of the cardiac 
nerves comes from the spinal accessory and the 
superior cervical nerves. Longet{ mentions 
that he failed in influencing the rhythm of the 
heart by the application of galvariism to the 
vagi in dogs, rabbits, and sheep, but very fre- 
quently succeeded by scraping the cervical 
cardiac branches of the vagus. Allowing that 
it is possible to increase the contractions of the 
heart by galvanic or mechanical excitation of 
the vagus or its cardiac branches, it must be 
admitted by every one that there is a very 
marked difference hetween the heart and volun- 
tary muscles in this respect, for all those who 
have failed in their experiments on the nerves 
of the heart, have felt not the smallest difficulty 
in producing contractions of the voluntary 
muscles by excitation of their nerves. The in- 
creased frequency of the pulsations of the heart 
observed during and for some minutes after the 
division of the vagi may be fairly referred to 
the struggles and terror of the animal, and the 
feeble and rapid pulsation of the heart which 
precedes death from this experiment is not 
owing to any direct effect upon that organ. 
The sudden death occasionally remarked after 
the division of these nerves, and which some 
of the early experimenters attributed to arrest- 
ment of the contractility of the heart, was in 
fact dependent upon the suffocation of the 
animal by the suspension of the movements of 
the muscles which dilate the superior aperture 
* Opus cit. p. 48, 62 and 66, 
+ Opus cit. p. 62. 
t Opus cit, &c. tom. ii. p. 314. 
- airto the lungs is prevented ;{| and V: 
PAR VAGUM. 
of the larynx. We have related several expe- — 
riments which appear to prove that when in- 
juries of the brain and mental emotions affect 
the contractility of the heart, the nervous influ- 
ence is not transmitted by the — branches 
of the vagi alone, but may also pass along 
the filaments of the sympathetic or ganglionic 
system of nerves. 
Pulmonary branches——Do the pulmonar 
branches of the vagus contain motor y 
We have made various unsuccessful 
to produce contractions in the muscular fibres 
of the bronchial tubes by excitation of the vagi 
in the neck.* Dr. C. T. B. Williams} was 
also unsuccessful on attempting this experiment, 
though he succeeded in producing contractions — 
in the bronchial muscular fibres by their direct 
excitation, as by transmitting galvanism through 
the substance of the lungs, &c. Longet and 
Volkmann have not only succeeded in exciting 
contractions of the muscular fibres of the — 
bronchii by direct stimulation, but also by ex- 
citants applied to the branches of the none 
To what extent are the pulmonary branches 
the vagus sensiferous? Brachet relates some 
experiments which seem to prove that the sen- — 
sation arising from the want of fresh air in the’ 
lungs, or the besoin de respirer, is annihilated 
by the division of vagi.§ Mr. Grainger|| re- 
peated one of Brachet’s experiments, and seemed 
satisfied that his conclusions were correct. 
periments against which he has not taken 
necessary precautions. 
We have satisfied ourselves by nume 
experiments that the sense of anxiety ari 
from the want of fresh air in the lungs 
nues after dividing the vagi when the access of 
and Longett+ from their experiments have also 
arrived at the same conclusion. It is possible 
that certain impressions which may excite t 
besvin de respirer are conveyed upwards to t 
encephalon through the medium of the syr 
thetic, but it is more probable that in the ex 
ditions induced by the experiment it was me 
immediately dependent upon the circulation 
ill-arterialized blood through the tissues of # 
body, and more especially through the 
phalon. We do not mean to deny that im 
pressions conveyed along the vagi to the e1 
phalon may not exeite the besoin de respirer 5 
the other hand, we believe that it is very pre 
able that this sensation as first felt, when 
respiration is suspended for a short time it 
healthy condition of the body, is dependent 
impressions conveyed along this nerve. W 
* Opus cit. for 1839. 
+ Transactions of British Scientific 
for 1840, p. 411. 
¢ Longet, opus cit. tom. ii. p. 289, and 
mann in Wagner’s Handwo ch der Ph 
logie, article Nervenphysiologie, p. 586. 
Systéme Nerveux Ganglionaire, p. 
On the Spinal Chord. 
Opus cit. for 1838. $e 
4 - : alles gy for -_. os aot ‘or 
ritish and Foreign Review for Jan. pe 2 
tt Opus cit. tom. ii., 291-2, 1842. ; 
