In many cases, the successive steps in the phenomena are not separately perceptible; but in the study of mental states,we do not question the succession of phenomena, although highly favourable instances only present them in their proper order. 21. With great circumspection in the choice of apparatus, and the amount of ether-vapour administered, it is possible, in many cases, to operate on the patient without loss of mental consciousness. The nature of the operation will be the best guide in

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... empts of this kind. In other cases, in order to avoid inconvenience from the jerks and contractions arising from reflex actions, total insensibility is desirable. 22. The theory of etherization advanced above, affords us many striking and instructive analogies with the action of other well-known agents-belladonna on the iris, infusion of tobacco on the heart, the Wourali poison. The last, as is well known, paralyzes the respiratory system of nerves, and destroys life by suspending the act of breathing. If an animal under its influence be made to breathe by an artificial force, the respiratory nerves awake from their temporary lethargy, and the animal lives. 22. After consciousness has been fully suspended by ethervapour, the several parts of the nervous system resume their functions successively. Music is heard before the patient sees, mental consciousness is restored before the sensibility to pain returns. 23. The action of ether-vapour on the ganglionic system, follows the sleep of voluntary and sensitive functions; the pulse is generally somewhat accelerated at first, especially when the vapour is very dilute; subsequently it lessens in frequency; ultimately, all parts of the system are reached, and life would be extinguished painlessly. This may be observed on small animals confined in ether-vapour. Mortimer-street, Cavendish-square, Apiil, 1847. ON THE