The cellular texture, after having covered the organs, enters every where into their intimate structure; it forms one of their principal elements. In an apparatus, which is an assemblage of many systems, each of these systems is united to the others by it; thus in the stomach, the intestines, the bladder, &c. different layers which belong to it separate the serous, muscular and mucous membranes of these different hollow organs. In the lungs, between the serous surface and the pulmonary parenchyma, between this and the divisions of the bronchia, between them and their mucous surfaces, it offers a variety of elongations more or less compact. In the organized systems, the cellular texture at first accompanies and surrounds, in their whole course, the vascular and nervous branches which enter into their composition; then it unites together the different homogeneous parts of each of them. Each fasciculus of a muscle, every muscular fibre, every nervous filament, every portion of aponeurosis and ligament, every glandular particle, &c. are surrounded with a sheath, a particular cellular layer, which in relation to its parts, is destined to the same uses that the greater covering of which we have just spoken, performs for the whole organ. Thus the life of each fibre is insulated by this layer, which, like that of the whole organ, forms around it a kind of atmosphere, destined to defend and protect it, but which can, however, like the general layer, and even more than that, because the parts are nearer to each other, be the means of the communication of diseases from one fibre to another. The motion of each of these fibres is peculiarly favoured by the cellular texture; thus the organs, which, like the muscles, have a very apparent motion in each of their parts taken separately, are capable by means of it of a much greater internal contraction, than those which, like the tendons, the ligaments, and the glands, have no sensible motion but that which is communicated to them.