(_b_) Cirrhotic liver. (_c_) Arterio-sclerosis, resulting in cerebral hæmorrhage (stroke--apoplexy--paralysis). (_d_) Locomotor ataxy. (_e_) Tuberculous peritonitis with adhesions. Now, in all these, the fibrous tissue is first deposited as an effort on the part of Nature to repair the damage done by an acute or chronic inflammation. But, unfortunately, not only does this fibrous tissue take the place of normal cells, whose activity is of the utmost importance in preserving the health of the individual, but it invariably tends after a time to contract; from which contraction further damage and the gravest results are likely to ensue. It will be observed that in its simplest form a fibrotic change is of the nature of real repair. Thus, after a deep cut or extensive injury to the skin, we all know that a ‘scar’ results. This affords admirable protection to the damaged area. Nor does the subsequent contraction seriously matter. Care has to be taken to allow for it in the treatment of extensive burns, and considerable allowance is made for contraction in the suturing of skin incisions made in the course of an operation. But except when the scar is on the face, where it is objectionable for cosmetic reasons, a contracting superficial scar is seldom a cause of serious inconvenience. But the case is very different in the kidney or the spinal cord. Contraction there causes an extensive destruction of delicate cells, and, by cutting off the blood supply, a great impairment of function, if not actual necrosis, of an infinite number of cells which were not directly affected by the preceding inflammation. And so the vicious circle goes on. Does Nature make no effort to play the part of the spear of Achilles and ‘heal the wounds which she herself has made’? Only to a negligible extent, on account of the vicious circle just alluded to. So we have the curious phenomenon that in the skin and round the broken ends of a fractured bone (for what is called callus is really only fibrous tissue with special bony elements superimposed) fibrous tissue is very slowly but more or less steadily absorbed; while in the places where such absorption would be of the utmost value to the individual it hardly takes place at all.