=Cutaneous hyperæsthesia= is that condition in which the slightest touch gives rise to an instant and extreme response. Some nervously organized mares which are dangerously ticklish and irritable, afford physiological examples. The surface soreness and sensitiveness which exist in the febrile chill, in wounds, dermatitis and neuralgia give pathological examples. It is further seen in certain cases of meningitis (cerebral and spinal), spinal irritations, rabies, tetanus and neuritis. =Hyperæsthesia to cold= is seen in neuralgia, rheumatism, the early stages of many fevers (chill), in myelitis, neuritis, nerve injuries, and in posterior (superior) spinal sclerosis. =Hyperæsthesia of the muscles= may be noted in tetanus, muscular rheumatism and neuralgia. _Visceral hyperæsthesia_ is shown in many cases of spasms of involuntary muscles (colic, arrest of intestinal calculi, gall stones or urinary concretions), and in inflammation of serous membranes (pleurisy, peritonitis). =Paræsthesia.= This is a painful or morbid sensation caused by a lesion in the central nervous structures or in the nerves, but referred by the sufferer to some peripheral organ over which such centre presides. It may even be referred to an organ or part that has been amputated or otherwise removed. This may cause lameness of a kind to indicate suffering in a given muscle, tendon or joint, when the cause is purely central. In dourine, sexual acts are excited which have their real source in the nerve centres. The rabid dog snaps at imaginary flies in mid-winter, when such insects are only phantoms of his brain. =Pressure on a nerve trunk= induces sensations of tingling, vibration, formication, heat, cold, and paresis, referred by the mind to the part to which that nerve is distributed, and when the pressure is removed these sensations recede in the order in which they came. This may explain some occult cases of lameness. =Itching= may be a pure, persistent neurosis without any skin lesion. Treatment should then be addressed to the nervous system. =Anæsthesia=, or absence of sensation, is in its degree partial or complete. The latter is familiar as occurring in parts the sensory nerves of which have been cut across, also in parts the sensory nerve or nerve centres of which have become completely degenerated. There is no response to the prick of a needle, the touch of a hot wire, to pinching or cutting. If the nerve remains intact as far as the spinal centres, reflex action may still occur, but the patient himself has no consciousness of this nor of the injury causing it. Accordingly, he makes no movement of head, ears, eyes, or other parts still dominated by the brain. In =partial or imperfect anæsthesia= the response to irritation is less marked and may be even delayed. In some forms of central lesions the response to a prick may be delayed two, five, or ten seconds, or even more.