In size gall-stones vary from the smallest pea up to a hen's egg. When several hundreds are contained in the gall-bladder, they will usually be of the dimension of a medium-sized pea. Two large solitary concretions in my possession are respectively 2 inches and 1½ inches in long diameter, and 1 inch and ¾ of an inch transversely. Very much larger calculi have, however, been recorded; thus, one mentioned by Frerichs is 5 inches in length and 4 inches in circumference. The most frequently encountered calculus, at least in this country, is polyangular in shape and of the size of a large pea. Globular or ovoid seems to be the prevailing form, and the dimensions that of a small pea, in Germany, according to Frerichs and Von Schüppel, but this statement must refer to the initial shape of these bodies.
Not all hepatic calculi have defined mathematical forms, but may consist of branching cylinders composed of irregular nodular masses, not unlike the concretions of inspissated bile. As a rule, in each case where the calculi are multiple there is uniformity of color, shape, and composition. This feature is well exhibited in my collection. The calculi obtained from each subject are in one case white, polyangular, rather unctuous, and nearly equal in size; in another, chestnut-brown in color, polyangular in shape, and varying slightly in size, but uniformly characteristic in shape; and in a third, singular in number, ovoid in shape, dark-brown in color.
In composition gall-stones vary somewhat. When fresh they contain considerable water, and at all times are hygroscopic. Dried in the air, they are composed of—
| Water | 4 |
| Solids | 96 |
| 100 |
The solids consist of—
| Cholesterin | 98 |
| Pigment | 1 |
| Inorganic or mineral matter | 1 |
| 100 |
Such are the constituents, according to Harley, of the usual concretion, the cholesterin calculus. But as other varieties are encountered occasionally, it may be well to give the composition of these. The following table by Ritter, to be found in Robin's Journal for 1872 (p. 60), is a correct representation of the contents of different specimens:
| Composition of Different Kinds. | 1st. | 2d. | 3d. | 4th. | 5th. | 6th. | 7th. | 8th. |
| Cholesterin | 98.1 | 97.4 | 70.6 | 64.2 | 81.4 | 84.3 | trace. | 0 |
| Organic matter | 1.5 | 2.1 | 22.9 | 27.4 | 15.4 | 12.4 | 75.2 | 18.1 |
| Inorganic matter | 0.4 | 0.5 | 6.5 | 8.4 | 3.2 | 3.3 | 24.8 | 91.9 |
| Number of specimens | 28 | 16 | 580 | 94 | 220 | 16 | 3 | 1 |
The above may be regarded as the average composition, expressed in round numbers. The variations from these figures will be comprehended in two parts.
A calculus consists of three several parts: the nucleus, the body, the rind. A calculus of small or medium size may be a nucleus for the formation of a large one. Usually the nucleus consists of a bit of mucus, casts of the biliary ducts (Thudicum), inspissated bile, a blood-clot, a liver-fluke or other parasite, as a desiccated round-worm, or some foreign body, as a seed, or, as in one reported example, a globule of mercury.155 The central mass of mucus may contain a large proportion of pigment or crystals of cholesterin or lime-salts, giving it special characteristics.156 There may be several nuclei. Fauconneau-Dufresne reports an instance in which a pyramidal concretion contained four, and Guilbert a globular stone with five, distinct nuclei. Such examples of calculi having multiple nuclei are produced by the adhesion whilst in a soft state of two or more, and the subsequent addition of material to the conjoint mass, welding it into a single stone. A few calculi are homogeneous throughout, composed of nearly pure cholesterin, mixed intimately with a little coloring matter and lime salts. The cholesterin calculus will have a somewhat translucent appearance, will be a dead white or a yellowish-white, or present a greenish- or brownish-yellow tint through the white. Even the white calculus, apparently composed of nearly pure cholesterin, will be found on section to contain traces of a nucleus. By long detention in a gall-bladder whose duct is permanently occluded, and is therefore free of fluid, the mucus nucleus may so shrivel as to leave a cavity which is merely stained. One of my specimens—a solitary calculus of large size—exhibits this peculiarity.