The injection, however, only cleanses the sinuses, and the nose also becomes involved by the disease. It is usual to describe the turbinated bones, or the fragile bones situated within the nostrils, as thin osseous structures, making numerous convolutions upon themselves. They favor such an opinion when viewed _in situ;_ but, being removed, are found to consist of ample sacs or bags, which the external layer concealed from view. These hidden spaces soon fill with pus; here it remains; the position of the head even cannot entirely dislodge it, as the head is seldom carried perpendicularly. Here the pus hardens or concretes, until by degrees the cavities are filled with a foul and solid matter. [Illustration: THE TURBINATED BONE WITHIN THE NOSTRIL OF A HORSE AFFECTED WITH NASAL GLEET; PARTLY ABSORBED BY PRESSURE AND PARTLY DISTENDED BY AN ACCUMULATION OF CONCRETE PUS. ] [Illustration: PART OF A HORSE'S HEAD WHICH HAS THE BONE TREPHINED SO AS TO ENABLE THE SURGEON TO EMPTY THE TURBINATED BONE. THE COURSE OF THE NERVES IS SHOWN. ] Such a store-house of disease may thus be opened and cleansed. Mark with chalk or charcoal the spot in a line with the infra-orbital foramen, and a little anterior to the third molar tooth the positions of both may be clearly ascertained by feeling externally upon the head of the living horse. At that place cut through the skin, but no deeper. Make a T incision, only reverse the letter ⊥. Withdraw the two flaps of skin; remove by means of blunt hooks any structures that conceal the bone, upon which last, when clear, employ the trephine. The side of the face being opened, insert through the opening a steel probe. Thrust it through the concrete pus, and strive to discover the most depending portion of the sac. To this spot, if possible, apply a hollow metallic tube, about twelve inches long. This instrument has a horn-shaped mouth at the blunt extremity, and a fine sharp steel saw at the other. The saw being fixed upon the spot indicated by the probe, and a few revolutions being given to the horn-shaped end, between the palms of the hands, a circular portion of the bony net-work which characterizes the turbinated structures is removed. [Illustration: FIG. 2. Fig. 1. The hollow metallic tube, having at one extremity a horn-shaped mouth for the convenience of inserting a gum-elastic probe, and at the other end a fine saw for cutting through the turbinated bone. Fig. 2. _a._ A gum-elastic probe to be threaded through the metallic tube, and so forced out of the nostril. _b._ A portion of string passed through the eye of the probe and forming a loop. _c._ The tape which constitutes the seton passed through the looped string. ]