ultimately develop into typical tendon cells, and the fibres which they form constitute the new tendon fibres.  Under aseptic conditions repair is complete in from two to three weeks.  In the course of the reparative process the tendon and its sheath may become adherent, which leads to impaired movement and stiffness.  If the ends of an accidentally divided tendon are at once brought into accurate apposition and secured by sutures, they unite directly with a minimum amount of scar tissue, and function is perfectly restored.

Muscle.—­Unstriped muscle does not seem to be capable of being regenerated to any but a moderate degree.  If the ends of a divided striped muscle are at once brought into apposition by stitches, primary union takes place with a minimum of intervening fibrous tissue.  The nuclei of the muscle fibres in close proximity to this young cicatricial tissue proliferate, and a few new muscle fibres may be developed, but any gross loss of muscular tissue is replaced by a fibrous cicatrix.  It would appear that portions of muscle transplanted from animals to fill up gaps in human muscle are similarly replaced by fibrous tissue.  When a muscle is paralysed from loss of its nerve supply and undergoes complete degeneration, it is not capable of being regenerated, even should the integrity of the nerve be restored, and so its function is permanently lost.

Secretory Glands.—­The regeneration of secretory glands is usually incomplete, cicatricial tissue taking the place of the glandular substance which has been destroyed.  In wounds of the liver, for example, the gap is filled by fibrous tissue, but towards the periphery of the wound the liver cells proliferate and a certain amount of regeneration takes place.  In the kidney also, repair mainly takes place by cicatricial tissue, and although a few collecting tubules may be reformed, no regeneration of secreting tissue takes place.  After the operation of decapsulation of the kidney a new capsule is formed, and during the process young blood vessels permeate the superficial parts of the kidney and temporarily increase its blood supply, but in the consolidation of the new fibrous tissue these vessels are ultimately obliterated.  This does not prove that the operation is useless, as the temporary improvement of the circulation in the kidney may serve to tide the patient over a critical period of renal insufficiency.

Stomach and Intestine.—­Provided the peritoneal surfaces are accurately apposed, wounds of the stomach and intestine heal with great rapidity.  Within a few hours the peritoneal surfaces are glued together by a thin layer of fibrin and leucocytes, which is speedily organised and replaced by fibrous tissue.  Fibrous tissue takes the place of the muscular elements, which are not regenerated.  The mucous lining is restored by ingrowth from the margins, and there is evidence that some of the secreting glands may be reproduced.