(From cold, and to contract; for crystals were considered as water contracted by cold). See Crystallinae.

Crystalli tartari. See Tartarum. Crystallina. The crystalline humour of the eye, (from cold, and to contract).

Called also crystallinus humor; and discoides, from its resembling a disk or quoit of the Romans.

Immediately behind the aqueous humour is situated the crystalline; transparent, of the colour of crystal. It is situated between the aqueous and vitreous humours, its anterior part being opposite to, and very near the pupil; its posterior part is lodged in a cavity, formed for its reception in the middle and fore part of the vitreous humour: the figure of the crystalline is that of a lens, convex on both sides, but rather more so posteriorly. The crystalline is the least, but of the most firm consistence, of the three humours of the eye. It is more firm in the middle than in the sides; and, in time, is apt to change both in its consistence and colour, growing still more firm, and yellowish. It is invested with a dense, firm membrane, which is rather loosely connected to it; is perfectly transparent, but, when injected, appears furnished with numerous blood vessels. In the foetus there appears a branch of the artery that passes through the axis of the optic nerve,which comes through the vitreous humour, and ramifies through the capsule of the crystalline in a radiated manner; this is much larger in the foetus, and stronger than in adults: these branches go to the tips of the processus ciliaris, and are there imperceptible. The crystalline humour is membranous, and consists of many coats inclosed in one another; the whole of which are contained in a capsule, formed by a continuation of the covering of the vitreous humour. This capsule is called Aranea; q. v. The crystalline produces a second refraction of the rays of light; the first refraction, which is produced by the cor-and the aqueous humour, not being sufficient to bring them to a focus at the retina. More minutely examined, its specific gravity was found by Mr. Chenevix to be 1100. When fresh it was neither acid nor alkaline, but putrified rapidly. It is almost wholly soluble in water, and is partly coagulated by heat. Tanin gives a copious precipitate; but when free from the other humours, no traces of the muriatic acid were found. The proportion of water is therefore smaller; those of albumen and gelatine larger than in the other humours. Philosophical Trans. 1803, p. 197.