The vital properties are also very obscure in them. There is no animal sensibility in the natural state; it is only when inflammation or some other cause raises their organic sensibility, a sensibility which their functions necessarily suppose, it is only then, I say, that the brain perceives painfully the different irritations of which these organs are the seat. This becomes manifest, especially when foreign bodies are formed in the articulations, which suffer from their presence or are insensible to them, according as they irritate or not by their position, the cartilaginous extremities. There is neither animal nor sensible organic contractility in the cartilages; the insensible organic or tone alone exists in them, and this not in a great degree. The sympathies are obscure, almost wanting in the cartilaginous system. I do not know that in the acute affections of the different organs, we observe sympathetic phenomena of sensibility or contractility in them. They remain tranquil in the midst of the general derangement which affects the other systems in this sort of diseases. In chronic affections even, they experience but little alteration; examine, for example, comparatively, the body of a man that has died a violent death, which has left his organs untouched, and that of one who has died from phthisis, dropsy, cancer, &c. you will perceive between almost all their organs a striking difference; the aspect of the muscles, of the mucous and serous surfaces, of the vessels, the nerves, &c. is entirely changed by the slow alteration they have undergone in the second; in the midst of these alterations the cartilages are unchanged, their appearance is almost the same as in a natural state. _Character of the Vital Properties._