To form, therefore, a clear idea of these concretions it will be necessary to divide them into several classes, and refer them to the animals which produce them, and the climates and food which mostly assist in their production.
First, then, the stones formed in the bladder and kidneys of men, and other animals, must be distinguished from the class of bezoar, and described by the name of calculi, their substance being quite different from that of the bezoars; they are easily known by their weight, their urinous smell, and their structure, which is not regular, nor formed with concentric layers, like that of the bezoar.
2. The concretions that are often found in the gall-bladders and liver, of the human species, and other animals, must not be regarded as bezoars; they may easily be distinguished by their lightness, colour, and inflammability; besides they are not formed by layers encircled round a nucleus, as in the bezoar.
3. The balls frequently found in the stomachs of animals, and especially in those that ruminate, are not true bezoars. These balls, which are called ægagropili, are composed internally of the hair the animal has licked off his hide and swallowed, or from hard roots, which he could not digest, their external part is encrusted with a viscous substance, something like that of the bezoar. The ægagropili, therefore, have nothing in them, except this external layer, in common with the bezoar, and simple inspection is sufficient to distinguish one from the other.
4. Ægagropili are often found in the animals of temperate climates, but never any bezoars. Our oxen and cows, the Alpine chamois, and the porcupine of Italy, produce only ægagropili. Animals of hotter countries, on the contrary, only produce bezoars. The elephant, the rhinoceros, the goats, the gazelles of Asia and Africa, the lama of Peru, and others, produce, instead of ægagropili, solid bezoars, whose substance and size vary according to the difference of the animals and the climates in which they live.
5. The bezoars, to which such virtues and properties have been attributed, are the oriental kind, which, as we have said, proceed from goats, gazelles, and sheep, which feed on the mountains of Asia. The bezoar of an inferior quality, which is called occidental, proceeds from the lamas and pacos, which are found in the mountains of South America. In a word, the goats and gazelles of Africa also produce bezoars, but not of so good a quality as those of Asia.
From all these facts we may conclude, that, in general, the bezoar is only a residue of vegetable nutriment which is not to be found in carnivorous animals, and is peculiar to those who feed on plants; that in the southern mountains of Asia, the herbs being stronger than in any other part of the world, the bezoar, which is the residue of that food, has also more virtues than any other; that in America, where the heat is less, and the mountain herbs being weaker, the bezoars produced there are also inferior; and that in Europe, where the herbs are still weaker, and in all the valleys of both continents, where they are coarse, no bezoars are produced, but only ægagropili, which contain nothing but hair, roots, or filaments, which the animal was unable to digest.
[THE BUBALUS, AND OTHER ANIMALS WHICH HAVE AN AFFINITY TO THE GAZELLES AND GOATS.]