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The animals are divided into four groups. The first group is
kept under as nearly normal conditions as possible using ordinary
food and a rather soft water.
A small amount of lactic acid is added to the food and water
of the second group and of oxalic acid to that of the third group.
The fourth group is kept under normal conditions, except that
they are given water containing one part per thousand of chalk.
In almost every instance there is some deposition of salts on the
foreign bodies especially if the surfaces are rough. The salts consist
largely of calcium and magnesium phosphates.
Three dogs are given chalk water and powdered bone is added
to their food for three and a half months. No foreign bodies are
introduced into their urinary bladders and at necropsy all three dogs
are normal.
Human studies indicate that hard water is important under
certain circumstances. Urinary concretions are more common in
regions with a limestone soil. In this country certain " stone areas"
used to exist in the Eastern Counties, Westmorland, parts of Derbyshire
and North Wales, but these no longer remain, in Switzerland the
water is hard but urinary lithiasis is relatively rare. In Holland the
water is soft but there is plenty of lithiasis.
Clearly there are factors other than the hardness of the water.
It is probable that the astonishing "stone wave"of Central Europe
which apparently started about 1924 and was still continuing in 1938
was most likely an expression of a widespread change in the conditions
of life, and that dietary deficiency was a highly probable cause.
It is believed that the almost complete disappearance of vesical
calculus among the children of the poor today is again due to improved
nutrition. The part played by water supply in the occurrence of urinary
calculus under bad dietetic conditions was illustrated in South
Staffordshire where the disease diminished considerably when a softer
water than was formerly used was obtained by sinking wells to a deeper
level.
It is considered that it is in the presence of vitamin deficiency
especially in the amount of vitamin A that excess of lime in the water
is a factor in the formation of stone in the urinary tract. Such dietary
deficiency today could only occur under exceptional circumstances
and the formation of urinary stone now depends on numerous other
aetiological factors. These have been fully investigated by WinsburyWhite
(1954) who points out that the old conception that the presence
of stone depends largely on the ingestion of the chemical substances
of which the stone is composed has now faded into significance. He
points out that today the two commonest components of urinary
calculi are calcium oxalate and uric acid. Exclusion of calcium and
oxalate from the diet has no appreciable effect on the formation of
urinary stones. Uric acid stones are found quite commonly amongst
people whose diet never includes any protein. It is of special interest
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