If, at a late period in the case, the powers of life begin to flag, stimulants must be again had recourse to, and may now be pushed pretty freely, there being less risk of inordinate action ensuing, and much reason to fear that life can be prolonged only by the continued use of powerful means for the excitement of the system. Nor ought the surgeon to cease stimulating though the vital powers continue to diminish in spite of the treatment, and though the circumstances of the case may be so hopeless as to lead him to suppose that death cannot be further delayed; for many patients, who would otherwise have necessarily perished, have, by the continued use of stimuli, recovered under my care their sensibility, and been ultimately restored to health. Separation of the dura mater from the cranium, with more or less extravasation of blood between, sometimes takes place as a consequence of blows on the head, even though not severe. The blood may be absorbed, or an unhealthy abscess may form between the bone and membrane, attended with violent, dangerous, and, if neglected, fatal results. The internal mischief is not without external marks of its occurrence. If the scalp is undivided, a puffy tumour forms; and, when it has been injured, the wound degenerates, its surface is pale, and the discharge gleety; the exposed bone appears white and dry. It is also preceded by general disorder of the system, by restlessness and fever; there is sickness, occasional vomiting, shivering, pain of the forehead and back of the neck; in some cases, delirium and convulsions, and perhaps partial paralysis, and ultimately coma. All these symptoms, however, may exist without indicating precisely either the existence or the site of abscess, as I experienced in the following cases.