PHYSIOLOGY. 
eles of that function are so far independent continue after the former Iiave ceased, as 
of the will, that they act without any ex- 
ertion of volition, and continue their func- 
tions during sleep, when all the voluntary 
powers are suspended. AVhen the lover, 
plunged in a soft reverie, letches a deep 
sigh, the physiologist observes a strong 
and protracted inspiration, followed by a 
similar 'expiration ; crying and sobbing, dif- 
fer from sighing only in the circumstance of 
the expiration being interrupted, or divided 
into several distinct periods. In gaping, 
whicli is attended witii a sense of weari- 
ness, there is a large inspiration, accom- 
plished in a gradual manner, and by a kind 
of eiFoi't; the entrance of a great quantity 
of air is facilitated by opening the mouth 
wide : this is followed by a complete gra- 
dual expiration. Sneezing is a strong and 
violent expiration, and the noise accom- 
panying it is produced by the air passing 
cut with rapidity, and striking against the 
winding parietes of the nasal fossae. The 
effort, which is occasioned by the irritation 
of tlie pituitary membrane, is a convulsive 
motion of the muscles of respiration, and 
particuiarly of the diaphragm. In coughing 
the expirations are shorter and moye fre- 
quent ; the expelled air carries off the mu- 
cus lodged in the trachea and bronchiae, 
and tliis discharge constitutes expectora- 
tion. Laughing is a short inspiration, fol- 
lowed by several short and rapid expira- 
tions. 
The alternate dilatation and contraction 
of the cliest, proceed uninterruptedly from 
the moment of birth to the end of life, and 
in a healtiiy adult are repeated about four- 
teen times in a minute, so tliat each act of 
respiration corresponds pretty nearly to five 
pulsations of the heart. For an account of 
the clianges wliiclr the blood experiences in 
respiration, as well as tliose which take 
place in tlie respired air, and for the com- 
position of the blood itselfj see Respira- 
tion and Blood. 
The action of the lungs upon the blood is 
so essential to tlie continuance of life, tliat 
its interruption very speedily causes death. 
Yet in these cases absolute death does not 
occur instantly, but the vital processes, al- 
though suspended fora time, may be renew- 
ed by a proper treatment ; and lienee arises 
the possibility of recovering the apparently 
dead from drowning, <ic. On tlie subject 
of sudden deaths, we may observe, that the 
organic functions may subsist after the ani- 
mal are extinguished, as in apoplexy, con- 
enssion, &c. The latter, however, never 
VOL. V. 
in great liaeniorrliages, wounds of the iieart, 
asphyxia, &c. Hence tlie cessation of or- 
ganic life is a sure indication of general 
death, while that of animal life is a very 
fallacious one. 
In explaining the effect which the cessa- 
tion of respiration produces, some have 
stated, that the lungs, being no longer dis- 
tended by tlie air in inspiration, liave tiieir 
vessels folded, and consequently mecliani- 
cally unfit for the circulation of blood 
through them. Bichat, in liis excellent 
“ Reclierches sur la Vie et la Mort,” has 
fully disproved this statement, and lias 
shown, by incontrovertible experiments, 
that neither the empty state of tlie lungs in 
complete expiration, nor their distended 
condition in the most full inspiration, pro- 
duces any obstacle to the passage of blood 
through the pulmonary vessels. He proves 
likewise, that when the cessation of the 
chemical plienomena of the lungs induces 
a cessation of the heart’s action, this does 
not happen in consequence of the simple 
contact of black blood with the internal 
surface of the left ventricle ; but in conse- 
quence of this blood, thus deprived of those 
principles whicli are necessary for main- 
taining- the actions of parts, penetrating the 
tissue of tlie lieart, arid coming into con- 
tact with its fibres. The brain is affected 
in the same way, in consequence of the 
cessation of respiration ; and the arrival of 
venous blood in this organ, causes an imme- 
diate cessation of animal life, while the or- 
ganic still subsists. The same blood too, 
accumulated in every other structure, pro- 
bably affects the whole body with its mor- 
tiferous qualities ; and consequently, a me- 
ciianical inflation of tlie lungs witli pure air, 
is tlie most powerful raetiiod of recovery 
that can be adopted in these cases. 
Tile term asphyxia, signifying absence 
of the pulse, is applied to every apparent 
loss of vitality, produced by an external 
cause tliat suspends respiration, as drown- 
ing, strangling, disoxygenation of the air 
we breathe, &c. Tlie difference between 
asphyxia and real death is, that in tlie for- 
mer state the principle of life may be re- 
animated, while in tlie latter it is com- 
pletely extinct. In those cases where it 
arises from drowning, strangulation, and 
some of the non-respirahle gases as carbo- 
nic acid ; the cessation of respiration is the 
cause, and tlie treatment must be con- 
ducted on the principles just mentioned. 
Where noxious vapours, as those of privies, 
A a 
