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.

Foreign bodies encapsulated in the peritoneal cavity are specially dangerous, as the proximity of the intestine furnishes a constant possibility of infection.

The question of removal of the foreign body must be decided according to the conditions present in individual cases; in searching for a foreign body in the tissues, unless it has been accurately located, a general anaesthetic is to be preferred.

BURNS AND SCALDS

The distinction between a burn which results from the action of dry heat on the tissues of the body and a scald which results from the action of moist heat, has no clinical significance.

In young and debilitated subjects hot poultices may produce injuries of the nature of burns.  In old people with enfeebled circulation mere exposure to a strong fire may cause severe degrees of burning, the clothes covering the part being uninjured.  This may also occur about the feet, legs, or knees of persons while intoxicated who have fallen asleep before the fire.

The damage done to the tissues by strong caustics, such as fuming nitric acid, sulphuric acid, caustic potash, nitrate of silver, or arsenical paste, presents pathological and clinical features almost identical with those resulting from heat.  Electricity and the Rontgen rays also produce lesions of the nature of burns.

Pathology of Burns.—­Much discussion has taken place regarding the explanation of the rapidly fatal issue in extensive superficial burns.  On post-mortem examination the lesions found in these cases are:  (1) general hyperaemia of all the organs of the abdominal, thoracic, and cerebro-spinal cavities; (2) marked leucocytosis, with destruction of red corpuscles, setting free haemoglobin which lodges in the epithelial cells of the tubules of the kidneys; (3) minute thrombi and extravasations throughout the tissues of the body; (4) degeneration of the ganglion cells of the solar plexus; (5) oedema and degeneration of the lymphoid tissue throughout the body; (6) cloudy swelling of the liver and kidneys, and softening and enlargement of the spleen.  Bardeen suggests that these morbid phenomena correspond so closely to those met with where the presence of a toxin is known to produce them, that in all probability death is similarly due to the action of some poison produced by the action of heat on the skin and on the proteins of the blood.