_The eyelids_ are usually half open, and the eyeballs at rest looking forward and slightly downwards. An extreme rotation downward may usually be taken as a sign of very deep anæsthesia. _The pupil_ is, as already said, always active to light, but its actual size varies with the anæsthetic used. With ether, particularly “closed” ether, it may be large (4–5 millimetres): with open ether, preceded by morphia, about 3–4 millimetres: a good chloroform anæsthesia usually exhibits a pupil of only 2–3 millimetres, and if morphia has also been given, it may be pin-point in size. Too much emphasis must not be placed, however, upon the mere size of the pupil; that may vary within wide limits without necessarily indicating serious abnormality. The essential point is that the light reflex shall be brisk. A pupil of 5 millimetres reacting sharply to light may be of no special moment: one of that size immobile to light would cause real anxiety. _The conjunctival reflex_ usually disappears fairly early in the third stage: if briskly present, the anæsthesia is certainly a light one, and probably insufficient for an abdominal section. _The corneal reflex_ if properly taken in the way already described can usually be elicited throughout the third stage. In an anæsthesia deep enough for abdominal section it is, of course, not brisk, but we may say generally that its entire absence is _presumptive_ evidence of a very deep anæsthesia--probably undesirably deep. It must not be forgotten that some local causes such as drying of the surface of the cornea may cause it to disappear, and in case of doubt it is sometimes worth while to wash out the eye with a little saline solution. If after doing so the anæsthetist still finds the reflex not present he should be on his guard. Provided, however, that the light reflex is still present and colour and respiration satisfactory, he need not consider that the patient is in any immediate danger. Broadly speaking, then, the third stage, the stage which is called for by the requirements of major surgery, is characterised by (1) full regular respirations; (2) colour not much removed from normal; (3) moderate sized pupil, larger in the case of ether than chloroform; (4) conjunctival reflex faint or absent; (5) corneal reflex just present, or, in a deep third stage, just absent; (6) light reflex present: these may be regarded _as the signs of fully developed surgical anæsthesia_.