(f.) Salzvary calculi.— The calculous accu mulations met with not very unfrequently in connection with the salivary glands, are com monly regarded as depositions from the sa liva, and may be generically termed ptyaliths (rrvctitoy, saliva, and itiffoc, a stone). But they are at the least depositions from saliva of morbid composition, for while they are essen tially formed of phosphate of lime t, this salt scarcely exists in the healthy fluid, and indeed is not enumerated among its ingredients at all by either Berzelius, Graham, or Wright. It be comes, therefore, extremely probable that the excess of phosphate is generated through the influence of irritation of mucous membrane. Salivary calculi are of much more common occurrence in some of the lower animals (e.g. the horse, ass, and dog) than in the human subject.
The parotid gland is less frequently the seat of these products than the submaxillary and especially than the sublingual gland. Polker extracted an encysted stalactiform calculus, 15 lines long, 9 broad, and weighing 120 grains, from the parotid, composed of phosphate of lime and animal matter. Breschet describes white calculi of scaly fracture, some of them crystallized in regular tetrahedra, and having a nucleus composed of a grain of oats, which were discovered in the maxillary glands of an elephant : here, in addition to phosphate of lime and animal matter, there was carbonate of lime. The affection called ranula is produced by obstruction of the ducts of the sublingual gland with calculous matter, which may form a single large mass, or be united into numerous minute ones. Chronic inflammation and ab scess are the frequent results of such accu mulations.
Of similar origin is the calculous matter which gathers round the teeth, commonly called tartar or odontoliths (okw, a tooth, and xteor, a stone). Two kinds of tartar have been distinguished by Duvall : a, tartar of deep grey or even blackish colour, hard and com pact, smooth on the surface, breaking ahnost like glass, and forming first on the root of the tooth, whence it spreads to the enamel ; b, tar tar of yellowish colour, less compact, friable, less smooth on the surface, forming on the enamel near the gums, whence it spreads to the crown in the majority of cases, but sometimes insinuates itself under thegums. Tartar appears first as a thin layer of slimy matter, which hardens ; another layer is then deposited, hardens in its turn, and so on. It accumulates enormously in some instances, exceeds the tooth (to which it is often most firmly united) Bulilmann * has recently drawn attention to certain microscopical corpuscles, most fre quently met with on teeth surrounded with tartar, yet not altogether absent from the cleanest. Originally described by Leeuwen
hoeck, these bodies are of filiform shape, and found in three conditions : a, yellowish fibres usually collected into tufts ; b, the same fibres broken and scattered atnong the epithelium-and mucus ; c, tufts of fibres mixed up with gra nular matter. They measure about 0.00006th of a Paris inch in breadth ; from qz-th to la line in length : they are smooth, arched, or wavy , somewhat elastic and transparent and of yel lowish white colour. The strongest nitric, sul phuric, and hydrochloric acids and caustic alkalies produce no change but that of render ing them a little more transparent : they are unaltered by heat. They are chiefly abundant at the junction of the tooth and gum. In fusoria (genera Vibrio and Monas) are also found in this substance.
(g.) The tonsils are not unfrequentIy the seat of phosphatic deposit. A calculus formed in one of the tonsils, of greyish white colour, containing an oval nucleus, was found by Wurzer to consist of phosphate of lime 63 8, carbonate of lime 16.7, animal matter 13.3, ptyalin with chlorides of sodium and potassium 7.1, iron and traces of manganese 0.1.t (h.) The pharynx and cesophagus have both been, though in extremely rare instances, the seat of calculous incrustations. Riviere and Bartholinus relate such cases.
(i.) Gastro.intestinal calculi.— The calculi discovered in th e intestinalcanalagree, as regards such saline materials as enter into their compo sition, in being essentially formed of earthy phosphates, especially that of lime. They may, however, be wholly free from saline matter.
Intestinal calculi are generally few in num ber, unless when of biliary origin : as many as thirty, however, were found in the stomach by Bilguer. Their size varies remarkably, from that of a nut to a mass larger than the clenched hand : their weight varies proportionally,—they have been known to weigh a pound and a half; two, and even four pounds. Their specific gravity is low, varying from 1000 to 1400. Their shape is irregularly rounded, the irregu larity being greatest in the largest masses, and, like biliary calculi, they affect their own forms mutually by lateral pressure. They occur in all parts of the intestinal tract, but are most common in the ccecum, large intestines, and stomach, and in rare instances have been dis charged by the mouth.