The adhesion is very great between the fleshy and tendinous fibre. Yet by macerating them a long time or subjecting them to ebullition, they gradually separate from each other. I have observed that in young subjects the union was much less intimate; thus by scraping at this age the tendon with a scalpel, we remove from it the muscle, without its ever appearing again; the polish is almost the same where the fibres are inserted, as where they are naturally wanting. The extremity of the tendon fixed to the bone, intermixes with the periosteum as it usually expands; so that it is with this membrane, and not with the bone itself, that the tendon makes part, because in fact it is the membrane which is of the same nature; thus if it finds an analogous membrane, it fixes to it equally, as we see in the insertion of the straight and oblique muscles in the sclerotica, of the ischio and bulbo-cavernous ones in the membrane of the corpus cavernosum. In general the tendons never unite but to fibrous membranes; the serous, the mucous, every organ in a word, foreign to the fibrous system, is also heterogeneous to them. II. _Organization of the Tendons._ The fibrous texture is extremely compact in the tendons; many appear homogeneous at first view; but by examining them with care, we soon distinguish fibres, connected by a small quantity of compact cellular texture. Ebullition renders these fibres very evident; when we plunge suddenly the tendon into boiling water at the place where it has been cut transversely, they become a little thicker at this divided extremity, swell as it were and are thus very evident. At the place where they expand to form an aponeurosis or to unite to the periosteum, these fibres can be distinctly seen without any preparation. On the other hand, as we can always, as I have said, reduce artificially a macerated tendon to an aponeurosis, and as in this state of maceration, soft and loose, it yields to all the forms we wish to give it, it is an excellent means of distinguishing the tendinous fibres. In this experiment so easily repeated, I have never seen the spiral form of the tendinous cylinders, of which some modern authors have spoken. These fibres are in the tendon as at the place where they separate to form an aponeurosis, that is to say in a right line.