which was made in the canal between the two constricted parts. [Illustration] Plate 58.--Figure 2. Fig. 3, Plate 58.--A calculus is here represented lodging in the urethra at the bulb. The walls of the urethra around the calculus appear thickened. Behind the obstructing body the canal has become dilated, and, in front of it, contracted. In some instances the calculus presents a perforation through its centre, by which the urine escapes. In others, the urine makes its exit between the calculus and the side of the urethra, which it dilates. In this latter way the foreign body becomes loosened in the canal and gradually pushed forwards as far as the meatus, within which, owing to the narrowness of this aperture, it lodges permanently. If the calculus forms a complete obstruction to the passage of the urine, and its removal cannot be effected by other means, an incision should be made to effect this object. [Illustration] Plate 58.--Figure 3. Fig. 4, Plate 58, represents the neck of the bladder and neighbouring part of the urethra of an ox, in which a polypous growth is seen attached by a long pedicle to the veru montanum and blocking up the neck of the bladder. Small irregular tubercles of organized lymph, and tumours formed by the lacunae distended by their own secretion, their orifices being closed by inflammation, are also found to obstruct the urethral canal. [Illustration] Plate 58.--Figure 4. Fig. 5, Plate 58.--In this figure is represented a small calculus impacted in and dilating the membranous part of the urethra. [Illustration] Plate 58.--Figure 5. Fig. 6, Plate 58.--Two strictures are here shown to exist in the urethra, one of which is situated immediately in front of the bulb, and the other at a point midway between the bulb and the meatus. [Illustration] Plate 58.--Figure 6. Fig. 7, Plate 58.--A stricture is here shown situated at the bulb. [Illustration] Plate 58.--Figure 7. Fig. 8, Plate 58, represents a stricture of the canal in front of the bulb. [Illustration] Plate 58.--Figure 8.