Both Serapion and Rhases mention the operation of puncturing the bladder. Rhases says that when there is retention of the urine and the bladder is inflamed, if the case be urgent, and there be reason to apprehend that the introduction of the catheter would aggravate the symptoms, it may be proper to make an incision in the perineum into the side of the bladder, and to draw off the urine with a canula. Both add, however, that there is danger of the wound not closing. (Cont. xxiii, 2.) The ancients seem to have fancied that it was necessary to fill up the internal cavity of the catheter with wool, or some such substance, in order to produce a vacuum when drawn out, believing that the catheter in this case acted upon the principle of the syphon. See Alexander Aphrodisiensis (Prob. ii, 59.) It is singular that they should have fallen into this mistake, when Galen, as we have mentioned above, had so clearly explained that the evacuation of the bladder is accomplished by the action of its expulsive powers whenever its retentive faculty is suspended or overcome. The earlier writers on surgery likewise adopt the notion that the cavity of the instrument requires to be filled up with wool. See Guido de Cauliaco (vi, 2.) They describe stricture of the urethra under the names of _hypersarcosis_ and _caruncula in meatu urinario_. See Henricus Regius (An. Med. 44.) SECT. LX.—ON CALCULUS. The cause of the formation of stones, and that in children they are formed most readily in the bladder, and in adults in the kidneys,—all this having been explained in another place, we now proceed to the method of performing lithotomy, but shall first give the symptoms of stones lodged in the bladder. The patients then void urine of a watery consistence with a sandy sediment; and from constant itching the member is now relaxed and again stretched in an uncommon degree, because, owing to the irritation, they are perpetually handling it, more especially in the case of children. When the stone falls into the neck of the bladder a sudden retention of urine takes place. Of those cut for the stone, children to the age of fourteen are the best subjects for the operation, on account of the softness of their bodies: old men are difficult to cure because ulcers of their bodies do not readily heal; and the intermediate ages have an intermediate chance of recovery. And again, those who have larger stones recover best because they have become habituated to the inflammation, whereas those who have smaller recover with difficulty for the opposite cause. These things being so, when we proceed to the operation, we first have recourse to shaking the patient, sometimes by means of assistants, and sometimes by making him jump from a height, in order that the stone may be forced down to the neck of the bladder. We have then to place him sitting in an erect posture, with his hands under his thighs, in order that the bladder may be forced down into a small space.