898 
and he has adduced in support of this view the 
statement of Cruveilhier that after the function 
of volition has been suspended by destroying 
the cerebrum, the respiratory movements are 
instantly arrested on dividing the vagi near 
their origin.* In putting this opinion to the 
test of experiment we found that though the 
respirations were very much diminished in 
pee see by the removal of the cerebrum 
and cerebellum and then dividing the vagi, 
they nevertheless continued for a longer or 
shorter time.+ Similar results have also been 
subsequently obtained by Volkmann,} . by 
Flourens,§ and by Longet.{| From these facts 
we are entitled to conclude that the vagi are 
not the sole excitors of respiration, and that 
ee may be made upon the medulla 
oblongata capable of exciting the involuntary 
Tespiratory movements after the vagi have been 
divided in the neck, and when impressions 
made on their expanded extremities in the 
lungs can no longer be conveyed inwards to 
the central organs of the nervous system. The 
importance of the vagi as incident nerves of 
a is not only proved by the marked 
and immediate diminution in the number of 
the respirations which follows their division,{ 
but also in a more striking manner by the 
morbid changes which take place in the 
lungs. 
Morbid changes in the lungs after dividing 
the vagi—The injury or division of the vagi is 
almost always fatal after a few days, even when 
precautions are taken to secure the free ingress 
of air into the lungs. The period of death in 
such experiments varies in different animals. 
Rabbits generally die earlier than dogs. The 
greater number of dogs die before the third 
day, and comparatively few live beyond the 
fifth day. In seventeen experiments upon dogs 
we found that eleven died before the completion 
of the third day, and seven of these eleven before 
the completion of the second day. Longet 
says that he | avalgey this experiment on 
thirty dogs, and they all died on or before the 
fifth day, and none of the rabbits operated on, 
lived beyond thirty-six hours.** Dupuy in 
his experiments found that horses lived to the 
fifth, sixth, and seventh day, when care was 
taken to admit a sufficient quantity of air into 
the lungs.t+ De Blainville informs us that the 
pigeons on which he operated died on the sixth 
or seventh day ;{{ and in the experiments of 
Arnold§§ upon hens and pigeons, these animals 
died between the second and fifth day. In 
tures,on the Nervons System, p. 25. Memoirs on 
the Nervous System, p. 87, 1837, 
* Lancet, 17th Feb., 1838, p. 733. 
+ Opus cit. for 1839. 
Opus cit. for 1840. 
Opus cit. Seconde edition, p. 204, Paris, 1842, 
Opus cit. tom. ii., p. 307, 1842. 
A diminution of the number of respirations, 
but to a less extent generally, results from dividing 
one of the vagi, ’ 
** Opus cit. tom. ii., p. 306. 
tt Journal de Médecine, Chirurg., &c., tome 
xxxvii., p. 356, Dec. 181. 
tt Nouv. Bullet. de la Societ. Philom. tome i., 
ann, ii., p. 226. 
§§ Opus cit. s. 163. 
. internal caloric which 
PAR VAGUM. 
eral the lungs are the only organs found in 
sa 'abeoisial state after death from injury or 
division of the vagi. We found the lungs 
unfit for the healthy performance of their fune- 
tions in fifteen out of seventeen dogs experi- 
mented upon. These organs arealmost always 
more or less congested with blood, ially at 
the depending parts, and the bronchial tubes 
and air cells frequently contain much : 
serum. In some portions — ~ lungs the 
congestion of blood is occasi so great as 
to Peacien them dense and devoid of air. This j 
condensation is not unfrequently greater in 
some parts than what can be accounted for by 
the mere congestion of blood in the vessels, and — 
probably depends in a great measure upon the — 
escape of the solid of the blood into the © 
tissue of the lung. The frothy serum has fre- 
quently a greater or less deep tinge of red. 
Portions of the lung are likewise occasionally _ 
found condensed from pneumonic effusion. — 
In seventeen experiments on dogs distinct evi- 
dences of pneumonia were observed in five, and 
in two of these it had run on to gangrene. 
These morbid changes upon the lungs are suffi- 
cient to explain the imperfect arterialization of 
the blood, and“ the diminished evolution of 
es death. We 
have endeavoured to prove that these morbi 
changes in the lungs are the result of the dit 
nished frequency of the respiratory moveme 
which immediately follows the division of the 
vagi. The vagi are the chief excitors of t 
respiratory muscular movements, and 
they are tied or divided the respirations am 
instantly diminished to less than half thei 
former number. The flow of blood throug! 
the lungs is dependent upon the continuane: 
of the respiratory process, and the great di 
nution in the activity of the respiratory muse 
movements must be followed by a retardatic 
and congestion of the blood in the lungs. Sue 
a congestion of blood, as is well kno 
generally followed by an effusion of sert 
and also predisposes the organsso cireumstanee 
to various morbid changes, chiefly of an infla 
matory nature. In the lungs this congestiol 
not only followed by the escape of the set 
but also of the more solid material from 
vessels, rendering the tissue dense. The 
fused serum is mixed up with air moving < 
the bronchial tubes during inspiration and 
piration, and it thus becomes frothy. A li 
blood may also extide from the congested 1 
cous membrane of the bronchial tubes, gi 
the serum there effused a reddish tinge. 
these changes proceed, the respi 15 
becomes more and more imperfect, the 
flowing along the arteries approaches more 
more to the venous hue, all the vital pro 
of the tissue are enfeebled, the internal te! 
rature sinks, and the animal dies of proti 
asphyxia. The division and other mjur 
the pneumo-gastrics have no direct effect u 
the production of the animal heat; t 
occasion this indirectly by enfeebling 
tion of respiration. We have else 
“ Edinburgh Medical and Surgical 
1839, By 
o 
Bf if 
me 
