FIG. 2, Plate 63.--The prostate, 2, 3, is enlarged, and the middle lobe, 2, appears bending the prostatic canal to an almost vertical position, and obstructing the vesical orifice. The bladder, 1, 1, 1, is thickened; the ureters, 7, are dilated; and a large sac, 6, 6, projects from the base of the bladder backwards, and occupies the recto-vesical fossa. The sac, equal in size to the bladder, communicates with this organ by a small circular opening, 8, situated between the orifices of the ureters. The peritonaeum is reflected from the summit of the bladder to that of the sac. A catheter, 4, appears perforating the third lobe of the prostate, 2, and entering the sac, 5, through the base of the bladder, below the opening, 8. In a case of this kind, a catheter occupying the position 4, 5, would, while voiding the bladder through the sac, make it seem as if it really traversed the vesical orifice. If a stone occupied the bladder, the point of the instrument in the sac could not detect it, whereas, if a stone lay within the sac, the instrument, on striking it here, would give the impression as if it lay within the bladder. [Illustration] Plate 63,--Figure 2. FIG. 3, Plate 63.--The urethra being strictured, the bladder has become sacculated. In the bas fond of the bladder appears a circular opening, 2, leading to a sac of large dimensions, which rested against the rectum. In such a case as this, the sac, occupying a lower position than the base of the bladder, must first become the recipient of the urine, and retain this fluid even after the bladder has been evacuated, either voluntarily or by means of instruments. If, in such a state of the parts, retention of urine called for puncturation, it is evident that this operation would be performed with greater effect by opening the depending sac through the bowel, than by entering the summit of the bladder above the pubes. [Illustration] Plate 63,--Figure 3, 4. FIG. 4, Plate 63.--The vesical orifice is obstructed by two portions, 3, 4, of the prostate, projecting upwards, one from each of its lateral lobes, 6, 6. The bladder is thickened and fasciculated, and from its summit projects a double sac, 1, 2, which is invested by the peritonaeum. FIG. 5, Plate 63.--The prostatic canal is constricted and bent upwards by the third lobe. The bladder is thickened, and its base is dilated in the form of a sac, which is dependent, and upon which rests a calculus. An instrument enters the bladder by perforating the third lobe, but does not come into contact with the calculus, owing to the low position occupied by this body. [Illustration] Plate 63,--Figure 5. FIG. 6, Plate 63.--Two sacs appear projecting on either side of the base of the bladder. The right one, 5, contains a calculus, 6; the left one, of larger dimensions, is empty. The rectum lay in contact with the base of the bladder between the two sacs. [Illustration] Plate 63,--Figure 6.