se are smoother, but
on the surface crystals of oxalate of lime may be detected with a lens.
Some renal calculi are formed of more distinct layers, more loosely
adherent to one another, and contain an excess of mucus, but no oxalate
of lime. Finally, a loose aggregation of small masses, forming a very
friable calculus, is found of all sizes within the limits of the pelvis
of the kidney. These, too, are in the main carbonate of lime (84 to 88
per cent) and without oxalate.

Symptoms of renal calculi are violent, colicky, pains, appearing
suddenly, very often in connection with exhausting work or the drawing
of specially heavy loads, and in certain cases disappearing with equal
suddenness. The nature of the colic becomes more manifest if it is
associated with stiffness of the back and hind limbs, frequent passage
of urine, and, above all, the passage of gravel with the urine,
especially at the time of the access of relief. The passage of blood and
pus in the urine is equally significant. If the irritation of the kidney
goes on to active inflammation, then the symptoms of nephritis are
added.

_Ureteric calculi._--These are so called because they are found in the
passage leading from the kidney to the bladder. They are simply small,
renal calculi which have escaped from the pelvis of the kidney and have
become arrested in the ureter. They give rise to symptoms almost
identical with those of renal calculi, with this difference, that the
colicky pains, caused by the obstruction of the ureter by the impacted
calculus, are more violent, and if the calculus passes on into the
bladder the relief is instantaneous and complete. If the ureter is
completely blocked for a length of time, the retained urine may give
rise to destructive inflammation in the kidney, which may end in the
entire absorption of that organ, leaving only a fibrous capsule
containing an urinous fluid. If both the ureters are similarly blocked,
the animal will die of uremic poisoning.

_Treatment of renal and ureteric calculi._--Treatment is unsatisfactory,
as it is only the small calculi that can pass through the ureters and
escape into the bladder. This may be favored by agents which will relax
the walls of the ureters by counteracting their spasm and even lessening
their tone, and by a liberal use of water and watery fluids to increase
the urine and the pressure upon the calculus from behind. One or two
ounces of laudanum, or 2 drams of extract of belladon