The dimensions of the vesical triangle are subject to individual variations. The triangle is usually equilateral, its sides varying from 1 to 1½ inches in length. The vesical orifices of the ureters are therefore situated at points lying from ½ to ¾ of an inch from the median line--a useful fact to remember in opening the bladder through the vagina. The vascular supply of the bladder is intimately associated with that of the uterus--a fact that explains the sympathetic disturbance of the bladder in uterine disease. The interior of the normal bladder is of a dull gray-red color. When distended, as in making an endoscopic examination, the minute arteries and veins may be plainly seen upon the surface. The pressure of the urine in the bladder may be determined by the manometer. In the erect posture the intra-vesical pressure has been found to vary from 12 to 16 inches of mercury. In the recumbent posture the pressure is reduced to from 4 to 6 inches. =Cystitis.=--Cystitis, especially of the subacute or the chronic form, is a common disease in women. The pathological changes resemble those seen in inflammation of mucous membrane in other parts of the body. In the acute stage the mucous membrane is swollen and relaxed, and of a deep-red or hyperemic appearance. Partial exfoliation takes place. The surface may be covered with thick, tenacious mucus or pus. In the chronic stage the mucous membrane is of a muddy gray color, and may be more or less covered with a muco-purulent secretion. Ulceration, superficial or deep, may occur. The ulcer is sometimes deep and ragged and extends into the muscular wall. In chronic cystitis we often find on the surface of the mucous membrane small localized areas of inflammation varying in size from ½ inch to 2 inches in diameter, and presenting a congested, granular, or eroded appearance, while the rest of the mucous membrane appears perfectly normal. These areas of inflammation bleed readily when touched. They are most often found in the base of the bladder, though they may occur in any part. When chronic cystitis is limited, it is usually confined to the vesical triangle. The outer coats of the bladder may be involved in the inflammatory process, and become much thickened and hypertrophied. The ureters and the kidneys may become in time affected, through direct extension of the inflammation in the form of a ureteritis and pyelitis, or through obstruction of the vesical orifice of the ureters from inflammatory thickening. The alteration in the character of the urine is usually marked except in the mild forms of chronic inflammation. The specific gravity is low, varying from 1005 to 1018. In the chronic disease the urine is alkaline and ammoniacal. It contains blood, mucus, pus, and epithelial cells from the vesical mucosa.