ANIMAL MATTER.
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Fromthe great complexity of the composition of animal substances, their decomposition is more rapid and its products more diverse than in the case of organic bodies of vegetable origin. While the carbon, hydrogen and oxygen give origin to the various kinds of ulmine and other substances of the same class, the nitrogen is generally valued as ammonia, and the sulphur as sulphurated hydrogen. It is the presence of these bodies that give to the putrefying substances the disagreeable odors by which that process is distinguished from mere mouldering and rotting.
Even during life, the constituent particles of the body are in a continual state of change, being absorbed and thrown out of the system, while others are assimilated in their place. Any part of our constituents, liquid or solid, which become unfitted for this vital function, is thereby killed, and must, if not got rid of, induce the death of the individual.
Hence, precisely the same means which give to theanimal substances the fixity of constitution which belongs to true chemical compounds, and thus preserve them from decomposition by the disturbing action of their own elements (as when we coagulate albumen by an acid, by corrosive sublimate, or by sulphate of copper), produce if applied to the living body the death of the part or the whole being by depriving the blood or the tissue of the mutability of constitution, which is required for the functions of the animal frame.
It is thus that the generality of metallic poisons act in producing death. Being absorbed into the system, they unite with the albumen and fibrine of the blood, and converting them into the insoluble compounds which we form in the laboratory, unfit them for the continual absorption and secretive offices, which, as organs, while they live they must fulfill. If the injury be local and limited in extent, the part so coagulated may be thrown off, and after a certain time the functions return to their proper order. If the mass, or the importance of the affected parts be greater, the system cannot so get rid of the portions which have thus been removed from the agency of life, to submit to merely chemical laws; on the contrary, the vital powers of the remaining portions of the animal are so much weakened in the effort that general death is caused.
For putrefaction it is thus necessary: 1st. That the force of vitality which governs so completely the mere chemical tendencies of the elements of our tissues be removed.
2d. That there shall not be present any powerful chemical reagent with which the organized material matter may enter into combination and thus the divellent tendencies of the affinities of its elements be overcome.
3d. That water be present in order to give the necessary mobility.
4th. That oxygen be present, or at least some other gas, into the space occupied by which the gaseous products may be diffused; and lastly, that the temperature shall be within moderate limits, putrefaction being impossible below 32° or above 182°.
The agency of the first of these preventive powers need not be further noticed. The second is extensively employed for embalming purposes, and in the preparation of bodies for anatomical studies, by baths, or injections into the arteries of solutions of corrosive sublimate, acetate of alumina, sulphate of iron, tannin, wood vinegar, and creasote; this last body, however, does not appear to act by direct combination, but by the complete (catalytic) coagulation it produces in all the tissues of the body that have protein for their base.
The necessity for the presence of water is shown by the fact that by drying the animal substances they are completely preserved. It is thus that the bodies of those perishing in the Arabian deserts are recovered years subsequently, dried, but completely fresh.
Alcohol and common salt both act in the preservation of bodies by their affinity for water. If a piece of flesh is covered with salt, the water gradually passes from the pores of the flesh, and dissolving the salt forms a brine, which does not wet the flesh, but trickles off its surface; the water necessary for putrefaction is thus removed.
Fourth, by excluding oxygen, the putrefactive process is retarded, precisely as the fermentative action of the gluten in grape juice cannot begin until a certain quantity of oxygen be absorbed. It is thus that meat that is sealed up in close vessels and then boiled for a moment is preserved; the small quantity of oxygen of the air remaining then in the vessel is absorbed, and the produce of that minute change being coagulated by heat it cannot proceed farther.
A high temperature stops putrefaction by coagulating the azotized materials; a temperature below 32° by freezing the water acts as if the tissues had been dried; in both cases putrefaction is arrested.
During putrefaction, at a stage prior to any fetid gas being evolved, a peculiar organic substance is generated,possessed of intensely poisonous properties, and the blood of persons who have died from its effects is found to be quite disorganized and irritating when applied to wounds.
This and the blood of over-driven cattle are found to produce effects similar to those of venomous reptiles, and the wounds received in dissection are sometimes followed by similar fatal consequences.The communication of disease in this way has recently been very ingeniously ascribed by Liebig to the general principle of the communication of decomposition by contact.
The small quantity of diseased organic matter originally introduced into the system by absorption, acts as a ferment and reproduces itself in the mass of the blood, until this becomes unfitted for the performance of its functions and the animal is killed; the active principle being thus copiously present, is exuded from the skin and lungs and gives a contagious character to the disease, or it remains only in the blood, or is secreted inpustules, constituting infection, by which the disease may be communicated to some other person.
This brief enumeration of the process of putrefaction will, to a certain extent, elucidate the process of embalming given in this book; it shows that the different methods herein explained, fulfill the conditions necessary to stop the progress of decomposition.
A most important point, and one which ought not to be passed upon without serious consideration is, the communication of disease by contact and absorption.
In a former part of this work, it has been suggested that too much care cannot be used in handling the bodies of persons who have died of certain diseases, especially when their bodies are to be subjected to the embalming process, which operation is rendered extremely dangerous to the embalmer from the factthat the hands must, perforce, come into direct contact with the denuded tissues, the blood, or some vitiated secretion of the body.
We shall, in the following chapter, find instances when the decomposition of certain parts of the body has taken place even before death. It is obvious that in such cases the utmost caution is necessary to avoid serious results.