This surgical operation derived its name from the kind of instrument used in it. We have recourse to it when a copious and hot defluxion is determined to the eyes. The face is ruddy, and about the forehead there is a sensation as of worms or ants passing along it. Having therefore first shaven the hairs about the forehead, we must permit the lower jaw to move, and avoiding the place where the temporal muscles are seen to act, we are to make three straight and parallel incisions on the forehead, each having the length of two fingers, and descending to the bone, and being at the distance of about three fingers’ breadth from one another. After the incision we apply the instrument called hypospathister, and extend the division from the left temple to the middle incision, dividing all the intermediate substance along with the pericranium; then we push a spatula from the middle one to the rest, and applying the point of a sharp-pointed knife to the first division, so that its sharp side may be turned to the flesh within the skin, and the blunt one to the bone, we push it as far as the middle division, cutting through all the vessels which descend from the head to the eyes, but not comprehending the external skin. And again we push it from the middle to the last incision, cutting through the vessels in like manner. After a moderate evacuation of blood, having squeezed out the coagula, and made three twisted tents, we are to put one into each division, and applying a compress soaked in water, we must secure it with a bandage. Next day we bathe not only the ulcers, but likewise the temporal muscles, and the ears with wine and oil, on account of the inflammation; and on the third day having removed the dressings, we must have recourse to copious affusion, and afterwards complete the cure suitably with tents out of basilicon dissolved in rose-oil. * * * * * COMMENTARY. See Aëtius (vii, 92); Albucasis (Chirurg. ii, 4); Haly Abbas (Pract. ix, 7.) This operation is better described by our author than by any of the others. Celsus, although he describes several grave operations for the relief of defluxions on the eyes, makes no mention of it. Aëtius barely alludes to it in general terms. It must have been a very formidable operation, and for that reason perhaps, has been entirely abandoned in moderate times. Even Albucasis speaks of it as being an operation which was performed by the ancients; from which language we may suppose that it had been given up in his time. His description of it is evidently taken from our author. Haly Abbas describes the operation very distinctly. Three longitudinal incisions at the distance of three fingers’ breadth from one another are to be made in the forehead down to the bone, then a knife, or some such instrument, is to be introduced so as to divide the parts between the longitudinal incisions, sparing only the outer skin. SECT. VII.—ON PERISCYPHISMUS.