We have seen that different productions belonging, by their nature, to the osseous or cartilaginous systems, are sometimes preternaturally developed in certain parts. Morbid anatomy also shows us productions, in which the fibrous appearance is very evident. I have many times made this observation in tumours of the womb, the fallopian tubes, &c. Instead of the lardy matter which is so common in these organic affections, we see one or several masses of fibres, very distinct, yellow, &c. I cannot however say that these excrescences belong essentially, by the substances that compose them, to the fibrous system, not having made upon them, experiments similar to those which I have made upon the organs of this system. ARTICLE FIFTH. OF THE FIBROUS MEMBRANES IN GENERAL. After having considered the fibrous system in a general manner, as it relates to its organization, its life, its properties and its nutrition, I shall now examine it more particularly in the great divisions it offers, and which we have pointed out above. I begin with the fibrous membranes. I. _Forms of the Fibrous Membranes._ These membranes which comprehend, as has been said, the periosteum, the dura-mater, the sclerotica, the albuginea, the peculiar membrane of the spleen, the kidneys, the corpus cavernosum, &c. are almost all destined to form external coverings, kind of sacs in which are contained the organs they invest. These organs are not, like those around which the serous surfaces are spread, as the stomach, the intestines, the bladder and the lungs, subject to alternate dilatations and contractions. This would not accord with their degree of extensibility. They are fitted exactly to the form of these organs, and have none of those numerous folds which we see in the serous membranes, if we except however the dura-mater. Their two surfaces are adherent; a character which distinguishes them especially from the preceding membranes, as well as from the mucous.