The reason that one foreign substance within the tissues is more or less irritating than another, is to be determined not alone by the character of the substance but also by how it influences the cells of the tissues involved. That environment influences cell life is well known. Aside from the effect of their food, cells may be influenced by temperature, electrically, by chemicals and mechanically. Our present purpose is to consider mechanical irritants.
In treatises on gunshot wounds it is presumed that the bullet is of lead, and the practice almost universally advised is to leave the ball undisturbed if it is not easily found. There is an adage generally recognized to the effect that "when a bullet has ceased to move it has ceased to do harm." The accompanying specimens (Figs. 1 and 2) of elephant's tusks, No. 1 with a lead bullet encapsulated, No. 2 with an
FLETCHER MH. TOLERANCE OF THE TISSUES TO FOREIGN BODIESWITH SPECIAL REFERENCE TO THE PULP AND GUMS.. JAMA. 1904;XLII(2):88-94. doi:10.1001/jama.1904.92490470016001d