Thus, the membrane (the conjunctiva) which lines the eyelids and covers the front of the eyeball is exquisitely sensitive to pain. We are reminded of this when anything touches the eye, or when a fly has lodged itself under the eyelid. And, when an operator wishes to ascertain whether his patient is sufficiently under the influence of chloroform he separates the eyelids and puts his finger gently upon the eye, knowing that if no indication be given, by flinching, that the impression made here is felt, it is probable that the patient will not be conscious of the more severe impression to be made by the knife elsewhere. Yet, this membrane is by no means pre-eminently endued with the sense of touch. Indeed, the very acuteness of its sensitiveness to pain quite unfits it for distinguishing the quality of the impressions made upon it. We know very quickly that something is in contact with the eye, but can form no idea what kind of substance it is, whether it be hard or soft, rough or smooth. In the hand, on the contrary, the sensitiveness to pain, though considerable, is not proportionate to the acuteness of the sense of touch. The sting of the rod on the palm, if my recollection serves me right, is not so sharply felt as it is upon that other region which shares with the hand the privilege of receiving the wrathful attentions of the master; and, yet, that other region is by no means distinguished for acuteness in the sense of touch. The mode in which sensitiveness to touch and to pain are adjusted in the hand and in the eye in relation to the functions of these two organs is one of the admirable features of their construction. Suppose the disposition to have been reversed--suppose the hand to have been as tender as the eye--of what use would it have been? The contact of a particle of dust would have caused agony; or, had the eye been no more sentient than the hand, it would soon have been destroyed by the chafing of foreign bodies upon its delicate surface.