CALCULI. 
837 
text-books, that urinary calculi are more common in the winter 
than at any other time of the year, as at this season stock are on 
dry feed and sometimes have insufficient water. A great or ab¬ 
normal drain of water from the system, by any other channel 
than the kidney, lessens the amount of water in the urine and 
predisposes the production of calculi ; as in cases of profuse 
diarrhoea or in excessive secretion of milk, etc. While the 
quantity of water in these cases is diminished, the waste of the 
tissues goes on as before, and if the waste matter is passed out 
through the kidneys it must necessarily be in a more concen¬ 
trated form. The kind of water drank by the animal may also 
be a factor in producing calculi. The concentrated condition of 
the urine which predisposes these deposits is favored by the 
quantity of lime salts that may be present in the water taken in. 
Feed which contains large quantities of phosphate of lime and 
other mineral substances entering into the composition of cal¬ 
culi, favor the formation of these stones. It is a noted fact that 
calculi are common among the different animals on limestone 
soils. Again, when little water is taken into the body and a 
large amount is expelled by the skin and through the respiratory 
tract and otherwise, the urine becomes small in quantity, but 
having to carry out its share of waste material from the tissues 
and the tissue-forming food, it becomes so charged with solids 
that it is ready to deposit them on the slightest disturbance ; if 
a little water of such concentrated urine is reabsorbed at any 
point in the urinary passage, the remainder is no longer able to 
hold all of the solids in solution and they are at once precipitated, 
forming a gravel or the commencement of a calculi. Urinary 
calculi may be found either in the uriniferous tubes, pelvis of 
the kidney, ureters, the bladder, the urethral canal or in the 
prepuce. It is said that if a foreign body be introduced into 
the kidney or bladder that a calculus will form around it, using 
it as a nucleus ; the explanation is that “ the foreign body carries 
with it bacteria which act as a ferment upon the urine and 
mucus, in addition to the mechanical injury caused by its 
presence, and if the substance passes through the body it carries 
