anæmia, as in starvation, after prolonged fever, after the withdrawal of customary stimuli, etc. These views are confirmed by the fact that some deliria cease upon the administration of sedatives and narcotics, while others are relieved and cured by rest, stimulants, and food. On the other hand, a large class of deliria, as exhibited in the insane, escape pathological analysis; for example, the delirious conceptions of monomania occurring in apparent somatic health and without well-marked symptoms of cerebral disease. We are much in the dark as to what the processes may be by which delusional notions grow in the subjective life and manifest themselves outwardly as deliria. It is probable that in such cases there is no material lesion (appreciable to our present means of research), but a morbid dynamic condition, false reactions, abnormal centripetal and centrifugal associations in the psychic mechanism, with or without inherited bias. The diagnosis of delirium as a symptom is usually easy, but it is a task of no small difficulty to determine its pathological associations in a given case, and to draw from this study correct therapeutic indications. {26} A careful review of the antecedent circumstances, of the patient's actual somatic condition, more especially as regards hæmic states and vaso-motor action, is indispensable. LOSS OF CONSCIOUSNESS, COMA.—Suspension of all sensibility, general and special, with loss of all strictly cerebral (cortical) reflexes, is met with in many pathological states. Its physiology or mode of production is unknown, but there are good reasons for believing that the lesion, vascular or organic, affects chiefly the cortical substance of the hemispheres. Its clearest manifestation, clinically, is after depressed fracture of the skull or after concussion of the brain, without or with abundant meningeal hemorrhage. In the last case unconsciousness or coma appears as an exaggeration of drowsiness or stupor; after a fall the patient may be able to walk into the hospital, but soon becomes drowsy, then stupid, and lastly completely insensible. In the first case, that of depressed fracture of the skull, the raising of the depressed bone is often followed immediately by return of consciousness; the patient seems to wake as from a deep sleep. In medical practice there are many analogous conditions of abnormal pressure causing coma, as in meningitis, cerebral abscess, hemorrhage, embolism of cerebral vessels, etc. Long-continued or fatal coma may be caused by general morbid states, as uræmia, acetonæmia, surgical hemorrhage, intoxication by narcotics, alcohol, ether, etc., and by asphyxia. Momentary loss of consciousness is induced in the various forms of epilepsy, lasting from a fraction of a second (so short as not to interrupt walking) to one or two minutes, followed by the more prolonged coma of the asphyxial stage. Temporary unconsciousness is also caused by physical or moral shock, but in many