The natural functions, as well as the morbid affections, have this slowness of the vital phenomena of the cartilages. The constant composition and decomposition, which their nutrition supposes, is not rapid. It requires a long time for nutritive substances to combine with them. I am persuaded that in animals which die suddenly from the effects of a carbuncle and whose muscles, glands, membranes, &c. almost instantly penetrated with the deleterious principles by the nutritive motion of composition, present an aliment so injurious, I am persuaded, I say, that these injurious principles not yet having penetrated the cartilages, these might be digested without danger. It is to the slowness of the motion of decomposition that must be attributed the slowness of the resolution of cartilaginous swellings; for tumours are resolved by the same laws that decompose our organs, as they are formed by the same laws that preside over their composition. The cartilages and the analogous organs, are to the other parts of the economy, as it respects their vitality, what the zoophytes and other animals with a capillary circulation only, are to the animals better organized, to those with a general circulation and those that have a heart with a double ventricle. As much as life considered in general in the series of beings that it animates, presents a difference in its activity, so much it differs in the same respect, examined in particular in the organs of each of these beings. ARTICLE FOURTH. DEVELOPMENT OF THE CARTILAGINOUS SYSTEM. The osseous and cartilaginous systems are confounded in the embryo; as the first is developed, the second contracts; the latter very evidently has gelatine for its principal base; I shall not return to the proofs that have demonstrated it in the osseous system. I have shown, in speaking of that system, how the cellular and vascular parenchyma, existing at first alone and constituting the mucous state, is penetrated afterwards with this base, which forms the cartilage. The primitive mode of the formation of these organs is then already known. Let us see how its development continues. I. _State of the Cartilaginous System in the first age._