Substances like paraffin, strands of silk used to bridge a gap in a
tendon, or portions of calcined bone, instead of being encapsulated, are
gradually permeated and eventually replaced by new connective tissue.
Embedded bodies may remain in the tissues for an indefinite period
without giving rise to inconvenience. At any time, however, they may
cause trouble, either as a result of infective complications, or by
inducing the formation of a mass of inflammatory tissue around them,
which may simulate a gumma, a tuberculous focus, or a sarcoma. This
latter condition may give rise to difficulties in diagnosis,
particularly if there is no history forthcoming of the entrance of the
foreign body. The ignorance of patients regarding the possible lodgment
in the tissues of a foreign body--even of considerable size--is
remarkable. In such cases the X-rays will reveal the presence of the
foreign body if it is sufficiently opaque to cast a shadow. The heavy,
lead-containing varieties of glass throw very definite shadows little
inferior in sharpness and definition to those of metal; almost all the
ordinary forms of commercial glass also may be shown up by the X-rays.
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