Bodies dying in high fever and edematous subjects are much more quickly decomposed than those dying with the ordinary wasting away disease.
The bodies of infants usually decompose more rapidly than those of adults, fat bodies more rapidly than lean ones.
The infectious diseases, intemperance, and the puerperal condition promote rapid decomposition as also does death from suffocation.
Poisoning from arsenic, alcohol, antimony, sulphuric acid, strychnine and chloroform may retard the progress of decay.
It is impossible, then, to say how long a body will keep without the use of preservatives, as it depends partly upon temperature, partly upon moisture, partly upon the amount of exposure and partly upon the conditions existing in the body before death.
We can easily understand the reason for all this if we understand the bacteriology relating to the subject.
In the first place, bacteria require for their best and most rapid growth the proper temperature, moisture and media relations. By this we mean that the temperature should be moderately warm, ranging from about forty to one hundred degrees Fahrenheit, the optimum being about the body temperature 98.6 degrees Fahrenheit or 37 degrees on the centigrade scale. With this optimum temperature, the element of moisture should always be present, as we find that nothing in nature will germinate without the necessary moisture. Then the bacteria must have the proper media, meaning that they must have the right substance on which to grow. Inasmuch as the cause of putrefaction is the host of putrefactive bacteria which abound trying to satisfy their own nutrition, and since these bacteria require a moderately warm and moist media on which to grow, it is only natural that putrefaction and decomposition should occur much more rapidly in warm moist climates than in dry cold climates.
In regard to exposure we learn that certain putrefactive bacteria are aerobic in character, i. e., that they need a great quantity of oxygen for their growth, and for this reason a body in water or buried in the earth does not decompose as rapidly as one exposed to the air. But although they do not decompose as rapidly yet we find that they do decompose in time. This is due to the fact that there is another class of bacteria, called anaerobic, i. e., which do not need oxygen for their growth. In the case of the body in water these anaerobic bacteria exist and develope slowly in the alimentary tract, and eliminate gases sufficient to bring the body to the surface, where the aerobic bacteria enter, and putrefaction progresses much more rapidly.
The starting point of decomposition is usually at the seat of the disease the subject had before death, but it soon spreads to all the various tissues of the body.
Putrefaction is always accompanied by a great amount of odor, which is caused by the generation of gases the result of bacterial action. The obnoxious gases, offensive to the smell are sulphureted hydrogen, nitrogen, carbonic acid and ammonia.