On the right side, a little below the ninth rib, the colon lies close to the gall bladder, and is, after death, sometimes tinged with bile. Posteriorly, this part of the colon is in contact with the kidney and duodenum. 86. =Bladder.=--When the bladder distends, it gradually rises out of the pelvis into the abdomen, pushes the small intestines out of the way, and forms a swelling above the pubes, reaching in some instances up to the navel. The outline of this swelling is perceptible to the hand as well as to percussion. More than this, fluctuation can be felt through the distended bladder by tapping on it in front with the fingers of one hand, while the forefinger of the other passed up the rectum feels the bottom of the ‘trigone.’ _THE PERINEUM._ The body is supposed to be placed in the usual position for lithotomy. 87. =Bony framework.=--We can readily feel the osseous and ligamentous boundaries of the perineum; namely, the rami of the pubes and ischia, the tuberosities of the ischia, the great sacro-ischiatic ligaments, and the apex of the coccyx. This framework forms a lozenge-shaped space. If we draw an imaginary line across it from the front of one tuber ischii to the other, we divide this space into an anterior and a posterior triangle. The anterior is nearly equilateral, and, in a well-formed pelvis, its sides are from three to three and a half inches long. It is called the urethral triangle. The posterior, containing the greater part of the anus and the ischio-rectal fossa on each side, is called the anal triangle. 88. =Raphé.=--A slight central ridge of skin, called the ‘raphé,’ runs from the anus up the perineum, scrotum, and penis. This ‘raphé,’ or middle line of the perineum, is the ‘line of safety’ in making incisions to let out matter or effused urine, or to divide a stricture. 89. =Central point of perineum.=--It is very important to know that a point of the raphé about midway between the scrotum (where it joins the perineum) and the centre of the anus, corresponds with the so-called ‘central tendon’ where the perineal muscles meet. The bulb of the urethra lies above this point, and never, at any age, comes lower down. The artery of the bulb, too, never runs below this level. Therefore the incision in lithotomy should never commence above it. A knife introduced at this point, and pushed backwards with a very slight inclination upwards, would enter the membranous part of the urethra just in front of the prostate gland; pushed still farther it would enter the neck of the bladder. This point, then, is a very good landmark to the urethra in lithotomy, or, indeed, in any operations on the perineum. The incision in the lateral operation of lithotomy, beginning below the point indicated, should be carried downwards and outwards between the anus and the tuberosity of the ischium, a little nearer to the tuberosity than the anus. The lower end of the incision should reach a point just below the anus.