Exposed to the action of the air, the fibrous system loses its whiteness by the evaporation of the fluids it contains; it acquires the horny hardening, becomes yellow, in part transparent and breaks with facility. Some days after having been dried, if replunged into water, it becomes nearly as white and soft as it was before; so that we can truly say, that its white colour is owing to water alone; this phenomenon takes place especially in the tendons. I have observed also in these last another remarkable phenomenon; it is that when they have macerated for some time, and are afterwards dried, they do not become yellow in drying, but remain of a very decided white. Without doubt the whole fibrous system would do the same.
The action of sulphuric and nitric acids quickly softens the fibrous texture, and reduces it to a kind of pulp, blackish in one and yellowish in the other; at the instant we plunge this texture into the acid, it crisps and contracts as in boiling water.
The fibrous texture resists in general putrefaction less than the cartilaginous; but it yields to it more slowly than the medullary, the cutaneous, the mucous, &c. In the midst of these putrid and disorganized textures in the subjects in our dissecting rooms, we find this still untouched; it finally becomes changed also. Water in which it has been macerated gives an odour less offensive than that which has been used for the maceration of most of the other systems.
More digestible than the cartilages and the fibro-cartilages, the fibrous texture is less so than most of the others. The experiments of Spallanzani and Gosse prove this. It appears that it yields to the action of the digestive juices in the same order as to maceration, ebullition, &c.; that is, 1st, the tendons; 2d, the aponeuroses; 3d, the different fibrous membranes; 4th, the ligaments, which are the most indigestible. I would observe however that when boiling has once softened the fibrous texture, it is all digested nearly alike. Thus the cartilages are as easy, and even more so, of digestion, than the tendons, when they have become gelatinous, as Spallanzani proved upon himself, though when raw they are much more indigestible.
II. Of the Common Parts which enter into the Organization of the Fibrous System.
The cellular texture exists in all the fibrous organs; but it is more or less abundant according as the fibres are more or less distant. In certain ligaments, it forms for the fibrous fasciæ, sheaths analogous to those of the muscles; in others, in the tendons, the aponeuroses, &c. we hardly perceive it; but everywhere it becomes very evident by maceration, by morbid affections, as, for example, by the fungi of the dura-mater, by the carcinoma of the testicle, which has seized the albuginea, by certain swellings of the periosteum, &c. In all these cases the fibrous texture relaxed, softened, preternatural, and of a spongy nature permits its fibres to separate and the cellular organ to appear. The development of fleshy granulations, the soft nature which these granulations have in certain wounds in which the fibrous organ is concerned, prove also the existence of the cellular organ there, which is in general in small quantity; this does not contribute a little to produce the resistance and the force of the organs that belong to it. Does this cellular texture contain fat? At first view we can hardly observe it, since we can scarcely distinguish this texture. Yet I have many times observed that by submitting to desiccation portions of aponeuroses, periosteum, dura-mater, &c. entirely stripped of every foreign part, when all these fluids had evaporated, and the organ had the appearance of parchment, a fatty exudation remaining on many places on its surface.
The existence of vessels varies in the fibrous system; much developed in some organs, as in the dura-mater, the periosteum, &c. they are less so in others, as the aponeuroses, and not at all in some, as the tendons. I would observe in general that it is in those in which they are the most evident, that inflammations and the different kinds of tumours are the most frequently observed. The affections of the dura-mater, the periosteum, &c. compared with those of the tendons, are a remarkable proof of this.
I do not know that absorbent vessels have been traced in the fibrous system.
The nerves appear to be equally foreign to it, notwithstanding what has been written on those of the periosteum, the dura-mater, &c. &c.