(Quasi cartilago, from carnis, the genitive of caro, flesh). A substance between muscular flesh and bone. A cartilage or gristle, called also chondros. Dr. Hunter defines it to be a smooth, solid, diaphanous, elastic, insensible, inorganic substance. He observes, that in the fresh subject it appears uniform, and without any visible fibres; when cut in any direction, its surface appears smooth, like wax or glue. On a cartilage there is no periosteum; but its place is supplied by a similar membrane, styled the perichondrium. Cartilages are the least affected by pressure of all animal substances, while the body is living: their substance is firm and dense, and their texture so fine, that, when cut, they appear only like a very stiff jelly. Cartilages are distinguished into three kinds: First, such as supply the place of a bone in an adult, as the trachea; secondly, such as supply the place of bones in young subjects, as epiphyses; and, thirdly, such as are common to the faetus and adult, and are expanded on the extremities of articulating joints.

Bones, it is supposed, are only cartilages, into which the calcareous phosphat has been secreted; and, when nitric acid has dissolved the latter, the shape of the bone is thought to be preserved by its cartilaginous substance. This, however, is not correct, as we have already shown; and the matter which remains after solution is rather membranous, with a portion of gelatine attached to the membranes.

Cartilages differ greatly from bone. They are insoluble in cold water.; but they yield to the water at a boiling heat, forming a jelly, and at last a glue. Yet, even to cold water, they impart a small proportion of gelatine, which becomes sour. The jelly procured by boiling water becomes first sour, and then putrid, but not in a high degree; and the animal matter procured by distillation is much less than from the same bulk of muscular, or almost any other animal, substance.

The articulating cartilages cannot be injected to their middle solid part, though the vessels of its membrane are easily filled. The cartilages are supposed to be supplied with nerves, but they are too minute to be visibly demonstrated.

The uses of the articulating cartilages are, first, to prevent abrasion, as without them the continual attrition of the bones against each other's surface must have destroyed them; secondly, by their elasticity, they break the force of collision; thirdly, they serve as indolent bodies, to admit of motion and friction without pain. They sometimes answer the purpose of ligaments, occasionally of bones.

A disease never affects the cartilages primarily. They are incapable of exfoliation; but when diseased from some preceding disorder of the bone, the whole is generally affected, and the cohesion between the cartilage and the bone in the joint being less than between the parts of the cartilage itself, causes it to separate from the bone. If a part of the cartilage is destroyed, it is never restored.