In operating on the carpal and tarsal bones for removal of caries, the surgeon must be well acquainted with the connexions and relations of the parts. If one bone is diseased, its removal will be sufficient; if several, the operation becomes more painful and difficult. When one only of the tarsal or carpal bones is almost completely destroyed, and the surfaces of those articulated with it are also more or less affected, it is not sufficient or safe merely to remove the loosely attached portions of the one primarily attacked; the diseased parts of those surrounding it must also be taken away, and it will often be necessary to apply the caustic afterwards. In caries of the distal range of bones, the bases of those supported by them are in general involved, and must also be removed. If one only is diseased, with the base of the metacarpal or metatarsal bone attached to it, the removal of these will be enough, and can be accomplished without difficulty. Some have recommended the total extirpation of a metacarpal or metatarsal bone, leaving the finger or toe appended; but the member, when thus left unsupported, can never become of any service to the patient, and may be productive of much inconvenience; whilst removal of them, along with the diseased bone, renders the operation much more easy of execution. If the whole disease can be extirpated, leaving the surfaces of the surrounding bones covered with healthy cartilage, the use of the caustic is not required, and would be productive of harm; but wherever it is impossible to avoid encroaching on the cancellated texture, such as of the os calcis, which it would be unsafe or imprudent to take away entirely, its use is then indispensable. After the removal of carious bones, the symptoms soon disappear, and the patient obtains a rapid, and often permanent cure. The instruments for these operations, and the method of performing them, will be afterwards mentioned. In conclusion, it may be remarked that the temporary cicatrix of a sore leading to a diseased bone has a very different appearance from the sound scar which is formed after its removal. The former is bluish, soft, on a level with the surrounding parts, and moveable; the latter is depressed, white, and firmly adherent to the bone.