_Aqueous Humor._ The aqueous humor, as has been pointed out by Uribe-Troncoso (Pathoginie du Glaucome 1903) contains a greatly increased quantity of albuminoids and inorganic salts in glaucoma. In acute glaucoma the increase of albuminoids (blood proteids) is greater than in chronic glaucoma. The aqueous humor becomes slightly turbid in acute attacks, coagulating more readily than the normal. The plastic principle contained in the aqueous is rarely sufficient to cause adhesion between the margin of the iris and the lens capsule, but the colloid nature of the aqueous, according to Troncoso, lessens its diffusibility and prevents its free passage into the lymph channels. The increase in albuminoids is a consequence of congestion and venous stasis and does not precede the attack. _Filtration Angle._ The changes that occur in the filtration angle before it is encroached upon by iris tissue are sclerosis of the ligamentum pectinatum in adults to which Henderson (Trans. Ophth. Soc. U.K. Vol. xxviii) has called our attention; the accompanying sclerosis of the other tissues to the inner side of Schlemm's canal; and, in some cases, the deposition of pigmented cells derived from the iris and ciliary processes (Levinsohn) which serve to obstruct the lymph spaces. In many of the cases of acute glaucoma and almost all of the cases of chronic glaucoma of long standing the filtration angle becomes blocked by the advance of the root of the iris. _Iris._ In acute glaucoma the iris is congested and thickened. It is pushed forward and may lie against the cornea at its periphery. When the attack subsides, the iris falls away from the cornea. Aside from the congestion, the primary changes that take place in the iris are indicative of paresis of the fibers of the motor oculi that supply the sphincter pupillae, and stimulation of the fibers from the sympathetic producing vasomotor spasm. The long diameter of the pupil apparently lies in the direction of the terminal vessels of the two principal branches of each long ciliary artery which form the circulus iridis major, where the vasomotor spasm would have the greatest effect in lessening the blood supply. The haziness of the cornea and slight turbidity of the aqueous contribute greatly to the apparent change in the color of the iris. In cases of simple chronic glaucoma there is but little evidence of edema of the iris. If the iris lies in contact with the sclera and cornea for some time, it becomes adherent (peripheral anterior synechia). As the disease progresses, the stroma of the iris atrophies and contracts. There is very little evidence of small-cell infiltration or the formation of cicatrical tissue. Numerous slits may develop in the iris through which the fundus of the eye may be seen (polycoria). The pigment layer does not atrophy in proportion to the stroma of the iris; by the contraction of the stroma of the pigment layer is doubled upon itself at the pupillary margin, forming a black