[Examples of signs of biogenic decomposition in bones long buried].

This investigation is based on twenty human bones, which mostly were stained red, black and violet, and always showed special dead bone decomposition, strictly limited to the stained areas. Histological examinations, biochemical and physical analysis in combination with microbiological isolation and cultivation tests could limit the cause of these phenomena to the biogenous sector--in this case microorganisms--and enabled the formulation of the following model on biogenous dead bone decomposition: Microorganisms are able to grow on buried bone by superficial settlement and invasion of physiological cavities. By means of excretion of enzymatic and acid metabolites for extracorporal dissociation of utilizable sources of energy the structural integrity of the tissue will be destructed. If this process is limited to the nearby environment of the growing organism, this leads to production of specific osteolysis (microscopical focal destruction). Expanded diffusion of enzymatic metabolites leads to leaching and departure of organic components, without producing microscopical focal destruction. The result is a shrinkage of the left material, that sometimes reminds of thermical influences. On the other side, an acidification of the medium by saprophagous microorganisms may lead to fractional crystallization of the mineral components by means of brushite-genesis. The result is further structural decomposition. In addition, the invading microorganism may excrete staining and fluorescing secondary metabolites into the bone, and impregnate the tissue durable. These processes are favoured in nearly isolated systems, like in crypts and stone coffins.