| than in man. 
_ shape, a dense structure, a smooth surface, and 
| a dead-white colour; they occur most frequently 
622 
accumulates upon the ill-kept teeth of man, and 
which is very hard and adhesive, and has a gritty 
structure and a dirty yellow colour, is a salivary 
calculus, and consists of phosphate and carbonate 
of lime. Calculi within the salivary glands some- 
times acquire so great a size, that they require 
to be extracted with the knife; but, in conse- 
quence of the greater expenditure of saliva, and 
the keener irritability of the salivary glands, they 
are much more frequent in herbivorous animals 
They have generally an oblong 
in the parotid gland; and when they become so 
_ large as to obstruct the flow of the saliva, and 
cause the perceptible distension of the duct, they 
| must immediately be removed by incision, else 
they will cause the duct to burst. A salivary 
calculus extracted from the gland of an ass was 
found by M. Caventon to contain 91°6 per cent. 
| of carbonate of lime, 4°8 of phosphate of lime, 
and 36 of animal matter; and a salivary calculus 
extracted from the mouth of a horse was found 
by M. Henry to contain 85°52 per cent. of carbo- 
nate of lime, 7°56 of carbonate of magnesia, 7°56 
| of phosphate of lime, and 2°48 of animal matter. 
Subcuticular calculi are formed beneath the 
skin, chiefly around the joints of the fingers and 
toes of man. They have an appearance some- 
| what similar to that of half-dried mortar; they 
| are popularly called chalk-stones ; and they have 
_ been found to consist principally of urate of 
soda. They are formed around the joints of gouty 
and rheumatic persons; and, in some cases of 
_ prolonged and severe rheumatism of the head, 
| they have been found between the skin and the 
| cartilage of the ear. 
They sometimes cause ul- 
ceration; and when they protrude through the 
skin, they can easily be removed. 
Gastric calculi occur chiefly in the rumen and 
the abomasum of ruminating animals. Some 
curious calculi of this class are noticed in our ar- 
ticle on Brzoars. Calculi in the stomachs of 
cattle vary in weight from a few ounces to six 
or seven pounds, and are exceedingly diversified 
in composition, and have generally, though not 
always, a somewhat spherical shape. “Those 
which are decidedly peculiar to cattle,” says Mr. 
Youatt, “are composed entirely of hair matted 
together by the mucous secretion from the folli- 
cular glands of the stomach. Sometimes they 
have no distinct central body; at other times it 
exists in the form of a bit of straw or wood, or 
frequently of stone or iron. They exist in the 
rumen andin the abomasum. Inthe abomasum, 
they are composed exclusively of hair, ir regularly 
matted and held together by the mucus of the 
stomach ; in the rumen, there is generally a mix- 
ture of Fol or earthy matter in the composition 
of the concretion. When simple food mingles 
with the hair, the ball seems to be formed by a 
succession of concentric layers, and in the centre 
isa bit of nail or stone; or, if the beasts have 
CALCULUS. 
access to running water, a piece of shell often 
constitutes the nucleus.” The hair is obtained 
by the practice which cattle have of licking one | 
another; and it sometimes occasions the forma- 
tion of large calculi in very young cattle. Cal- 
culi which contain but little hair are usually an 
agglutinated mass of earthy matter and the mate- 
rials of food, round a small piece of metal or some 
other hard central nucleus; and, though formed 
by concentric layers, they exhibit these in irre- 
gular thicknesses and confused succession. Many 
of the hard and spherical calculi of the rumen, 
when sawn asunder, display the concentric layers 
in a perfectly regular and beautifully marked 
condition, and are susceptible of a high degree of 
polish. Calculi are found chiefly in unthriving, 
lean, and sickly cattle; but whether they are the | 
cause or the effect of want of healthy tone in the 
stomach, is not known. 
intestinal calculi, in man, are usually sorrendPh 
agglutinations of fibrous and calcareous matter 
upon such nuclei as minute pieces of bone and 
small drupes of fruit. Most are smooth, compact, 
and comparatively light ; and some possess alter- 
nate layers of such earthy matter as- phosphate 
of lime, and such vegetable matter as the skin or © 
chaffy integument of oatmeal. They frequently 
occasion pains resembling colics; they encounter 
much less resistance to a passage toward the rec- 
tum than in quadrupeds; and, in most instances, 
they cannot be certainly known or even tolerably — 
conjectured to exist till they effect their escape, 
and cease to giveany trouble. Intestinal calculi, 
in horses, produce vastly more serious effects _ 
than in man, occasioning obstructions, inflamma- — 
tions, violent colics, ruptures of parts of the in- | 
testines, and not infrequently death itself. 
earthy and heaviest kinds of them vary in weight 
from a few grains to several pounds, and lie en- | 
sconced in the cells of the colon or the deep 
pouch of the cecum, and assume a diversity of 
shape according to the form of the nucleus on 
which they gather, or of the particular cell in | 
which they lie; and, in consequence both of the 
cavitous character of their retreat, and of the 
horizontal position of the whole of the animal’s | 
abdomen, they can make little or no way.toward 
the rectum, but are necessarily retained in their 
places till they become so large and heavy as to 
cause irritation and oppression at every move- 
ment of the animal, and eventually to produce 
fatal inflammation, or to rupture the cells or 
membranes in their vicinity. They occur most 
frequently in millers’ horses and various classes 
of heavy draught horses, and are supposed to be, 
in many instances, induced by combinations of 
bran with pulverized earths and stones. Other 
kinds of intestinal calculi, which often occur in 
the horses of millers and brewers, have irregular 
shapes and tuberculated surfaces, and consist 
principally of the filamentous portion of the grain 
of oats, and are supposed to be occasioned by the 
use of poor, thin, husky oats, and are sometimes 
oe 
The | 
