or CALLOSITY, in a general sense, any cutaneous, cornous, or osseous hardness, whether na- tural or preternatural; but most frequently it means the callus generated about the edges of a fracture, pro- vided by nature to preserve the fractured bones, or di- vided parts, in the situation in which they are replaced by the surgeon. A callus, in this last sense, is a sort of jelly, or liquid viscid matter, that sweats out from the small arteries and bony fibres of the divided parts, and fills up the chinks or cavities between them. It first appears of a cartilaginous substance; but at length becomes quite bony, and joins the fractured part so firm- ly together, that the limb will often make greater re- sistance to any external violence, with this part than with those which were never broken.

Callus is also a hard, dense, inflexible knob, rising on the hands, feet, &c. by much friction and pressure against hard bodies.