Stone in the bladder may be of any size, but in the ox does not usually exceed half an inch in diameter. There may, however, be a number of small calculi; indeed, they are sometimes so small and numerous as to form a small, pulpy magma by which the bladder is considerably distended. _Symptoms._--The symptoms of stone in the bladder may be absent until one of the masses escapes into the urethra, but when this occurs the escape of urine is prevented, or it is allowed to pass in drops or driblets only, and the effect of such obstruction becomes manifest. The point of obstruction is not always the same, but it is most frequently at the S-shaped curve of the penis, just above the testicles or scrotum. In cows and heifers the urethra is so short and becomes so widely dilated during the urination that the calculi easily escape in the flow of liquid and dangerous symptoms practically never appear. Even in the male the signs of illness are at first very slight. A close observer may notice the cylinders of hard, earthy materials encircling the tufts of hair at the opening of the prepuce. It may further be observed that the stall remains dry and that the animal has not been seen to pass water when out of doors. The tail may at times be gently raised and contractions of the muscle (accelerator urinÊ) beneath the anus (Pl. IX, fig. 2) may take place in a rhythmical or pulsating manner. As a rule, however, no symptom is noticed for two days, only the animal is lacking in his usual spirits. By this time the constantly accumulating urine has distended the bladder beyond its power of resistance and a rupture occurs, allowing the urine to escape into the cavity of the abdomen. Then dullness increases; the animal lies down most of his time; he becomes stupid and sometimes drowsy, with reddish-brown congestion of the lining membrane of the eyelids; pressure on the abdomen causes pain, flinching, and perhaps groaning, and the lowest part of the belly fluctuates more and more as the escaping urine accumulates in greater and greater amount. If at this stage the oiled hand is introduced into the rectum (last gut), the animal flinches when pressure is made downward on the floor of the pelvis, and no round, distended bladder is felt. If the same examination is made prior to the rupture, the rounded, tense, elastic bladder is felt extending forward into the abdomen, containing one or two gallons of liquid. There may be uneasy shifting of the hind limbs and twisting of the tail, also frequent lying down and rising, but these symptoms are exceptional. When the obstruction is low down between the thighs (at the S-shaped flexure), the line of the pulsating urethra from the anus downward may be felt distended with liquid, and though, by the hard swelling of the urethra, it is seldom easy to distinguish the exact seat of the stone, yet there is usually tenderness at the point of obstruction, and from this it may be accurately located.