'But a broad weapon if buried should not be extracted from a counter opening, lest to one large wound we add another; therefore it is to be extracted with a special variety of instrument which the Greeks call the Scoop of Diocles, since Diocles invented it. I have already stated that he was one of the most eminent of the old practitioners. Its blade of iron, or even of bronze, has at one end two hooks, one at each side turned backwards. At the other end it is folded over at the sides, and the end is slightly curved up towards that part which is bent. Moreover in it there is a perforation. This is introduced crosswise near the weapon, then when it comes near the point it is twisted a little so that it receives the point in the hole. When the weapon is in the cavity two fingers placed under the hooks at the other end simultaneously extract both the instrument and the weapon.' This description seems very definite until we attempt to reconstruct the instrument, when it becomes evident that more than one construction may be put on some parts of it. Pl. XLV, fig. 4, shows the instrument as conceived by me. CHAPTER IX BLADDER AND GYNAECOLOGICAL INSTRUMENTS _Catheter._ The catheter is very frequently referred to. Galen (xiv. 787) thus describes it: 'When urine is not passed on account of excessive dilatation of the bladder so that it cannot contract, we draw off the urine with a catheter. Therefore an instrument like the Roman letter S is let down into the bladder by the urethra. A thread is passed into it which has in its tip a little wool dipped in urine. Then it is drawn out and the urine follows it like a guide.' This method of preparing the catheter and the reasons for so doing are discussed at somewhat greater length in the following selection from Paul (VI. xix):