RESPIRATION and BLOOD.
The action of the lungs upon the blood is so essential to the continuance of life, that its interruption very speedily causes death. Yet, in these cases, absolute death does not occur instantly, but the vital processes, although suspended for a time, may be renewed by a proper treatment ; and hence arises the possibility ofrecover ing the apparently dead from drowning, &c. On the subject of sudden deaths, ire may observe, that the organic func Lions may subsist after the animal are tinguished, as in apoplexy, concussion, The latter, however, never continue after the former have ceased, as in great liwmorrliages, wounds of the heart, as phyxia, Ric- Hence the 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 ces sation of respiration produces, some hat stated, that the lungs, being no longer distended by the air in inspiration, have their vessels folded, and consequently me chanically unfit for the circulation of blood through them. I3ichat, in his excellent " Recherches sur la Vie et la Mort," has fully disproved this statement, and has shown, by incontrovertible experiments, that neither the empty state of the lungs in complete expiration, nor their distend ed condition in the most full inspiration, produces any obstacle to the passage of blood through the pulmonary vessels. He proves, likewise, that when the ces sation of the chemical phenomena of the lungs induces a cessation of the heart's action, this does not happen in conse quence of the simple contact of black blood with the internal surface of the left ventricle ; but in consequence of this blood, thus deprived of those principles which are necessary for maintaining the actions of parts penetrating the tissue of the heart, and coming into contact 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 immediate cessation of animal life, while the organic still subsists. The same blood, too, accu mulated in every other structure, pro bably affects the whale body with its mord tiferous qualities ; and consequently, a mechanical inflation of the lungs with pure air, is the most powerful method of recovery that can be adopted in these cases.
The term asphyxia, signifying absence of the pulse, is applied to every apparent loss of vitality, produced by an external cause that suspends respiration, as drown ing, strangling, disoxygenation of the air we breathe, &c. The difference between
asphyxia and real death is, that in the former state the principle of life may be re-animated, while in the latter it is com pletely extinct. In those cases where it arises from drowning, strangulation, and some of the non-respirable gases, as car bonic acid ; the cessation of respiration is' the cause, and the treatment must be con ducted on the principles just mentioned. Where noxious vapours, as those of pri vies, or burial places, or certain gases, as sulphurated and phosphorated hydrogen, produce it, there seems to be an action of some poisonous or deleterious substan ces on the nervous system through the medium of the lungs. Intoxication is quite different from asphyxia ; it induces protinind sleep, or insensibility, in which the pulse still beats, and respiration goes on, although slowly.
The lungs are organs of secretion, and separate from the venous blood, circulat ing through them in the pulmonary arte ry, and loaded with serum, a very abun dant watery vapour, called the breath, and spewing itself in separate globules when condensed by a cold and smooth surflice, as that of glass or metals. As the cessation of respiration is one of the most obvious and easily recognizable symptoms of death, the intimate connec tion between it and life has been noticed even by the vulgar, and hence life itself; and even the soul, have been supposed to reside in the breath. Thus inima, in La tin, denotes the breath, the life, or the soul. The breath of life is a familiar phrase in our own language, and the " animam efflavit" of the poet, which li terally means " blew out his breath," is employed to signify " died." We cannot admit that this watery vapour is formed by the oxygen of the atmosphere uniting with the hydrogen of the venous blood, as ibis combination, performed out of the body, is attended with phenomena of de flagration that do not occur in the pre sent instance. The quantity of this se cretion is said to equal that of the skin ; it should be distinguished from the mu cus secreted on the interior surface of the bronchi and trachea, which is thrown off by strong expirations, and forms the mat ter of expectoration.