(3.) Calculi formed wholly in the digestive passages are comparatively rare. They may consist of fces and inspissated secretions wholly (under which circumstances the name, calculus, is not in strictness applicable to them), or these may serve as a nucleus for the deposition of the ordinary phosphatic salts. White discovered, near the ilio-ccecal valve of a tuberculous subject, two masses (one weighing two, the other one and a-half pounds) com posed of a nucleus of indurated fmces, and a cortex of saline matter arranged in layers. Oleaginous matters sometimes accumulate in the intestine in the form and of the consistence almost of calculi. A mass of this kind, voided by a young tuberculous female, and examined by M. Lassaigne, was found to consist of These oleaginous formations will be presently further considered.
The oriental bezoard, a resinous intestinal calculus, chiefly met with in Certain species of goats and deer, appears (like ambergris in the whale) to be the result of morbid secretion from the bowels of the animal, and not to be composed (as was imagined by Vairquelin) of materials derived from its food. A very doubt ful case of calculus occurring in the hunzaa intestine, with close resemblance to ambergris in its characters, has been published by Dr. Kennedy.* We have lately examined some masses composed solely of fibrin, (Univ. Coll. Mus. presented by Dr. Rayner,) passed from the rectum after prolonged sufferings, simulating those of cancerous disease.
(k.) Balmy. (Gall stones, Choleliths). — Biliary calculi are found in every part of the system where the bile circulates, and even make their way occasionally into localities in which that fluid is not naturally found. Most com mon in the gall-bladder, they- are frequent in the larg,er ducts ; far less rare than has been affirmed by some writers in the radicles of the hepatic duet, not uncommonly encountered in their transit through the different parts of the intestine (where it is possible they may be sometimes actually formed), they are very rarely seen in the stomach.
Biliary calculi vary in number from one to several hundreds and even thousands : 3,646 are said to have been shown by Fuschius from the gall-bladder of a certain gladiarius ; and Dr. Parry t gives a case in which 2,654 were found in the same part. It is not uncommon to find one only, or two, three, or four; but observations are wanting as to the relative fre quency of small and large collections. Their size varies as their numbers. When single or few in number, they are comparatively large, have been known to reach the bulk of a hen's egg §, but rarely, even when single, exceed a walnut in dimensions ; when very numerous, they are sometimes scarcely larger than pins' heads, and some, of these small dimensions, may be associated with others of far greater bulk.
Their form likewise varies to a certain extent with their number. When single, the spherical, oval, or elongated shape predominates ; when numerous, they press upon and mould each other into cubic, pentagonal, or polygonal figures, with obtuse and rounded angles.
Their most common colour is greenish yel low ; but various shades of brown, green, dark or canary yellow, and even black or white, are observed. Their colour frequently varies in different parts of the mass ; and the differences of hue may either correspond to the lamelke of the calculus, or to the matters acting as the nucleus and the cortex respectively (the most common case), or be irregularly observable over the surface so as to produce a mottled appearance. Biliary calculi have a smooth surface and slightly unctuous feel.
When a biliary calculus is broken across, a distinction of nucleus and cortex is very com monlyseen. Complete homogeneousness, with out any lamellar or other obvious arrange ment, is extremely rare. The cortical portion generally consists of dull-looking lamellre ar ranged concentrically, but also striated trans versely. A tendency to the alternating charac ter of urinary calculi is sometimes visible : thus in the central point may appear a dark coloured and homogeneous matter irt small quantity (bile pigment), and from this shilling strata (cholosterin ) rad iate towards a cortex such as that above described (fig. 87.) The thickness of the cortex va ries in different parts; though generally greatest at the angles of polygonal calculi (fig. 87), this is not always the case. In a few instances on record a foreign body (e.g. a piece of needle) has been found forming the nucleus of a biliary calculus; such cases are of singular rarity, however, and for obvious reasons.
The constituents of biliary calculi are cho lesterin (the chief one) with other kinds of fat in small proportion, choleate of soda, bilifel linic acid or biliary resin mixed with bile pig ment, epithelium, and mucus. In some cases the mass is almost wholly composed of colour ing matter* ; in others of biliary resin and modified colouring matter, with mere traces of cholesterin.t Berzelius describes a gall-stone composed principally of carbon. Von Bibra $ discovered 1.5 per cent. of alumina with iron, and Lit per cent. of carbonate of lime in a biliary calculus ; the latter salt was also de tected by Witting in considerable amount. A calculus analyzed by Bally and Henry $ con sisted of carbonate of lime with traces of car bonate of magnesia 72.70, phosphate of lime 13.51, mucus with a little peroxide of iron and bile-pigment 10.81. Bertazzi* maintains cop per to he a constant ingredient of biliary calculi, having found it in every one of fourteen speci mens, apparently to an amount varying directly as the quantity of colouring matter present. Heller t confirms the statement of this chemist. Bertazzi failed in detecting copper in the bile collected from the gall-bladders of ten persons. In very rare instances calculi have been found composed of inspissated bile.