454 TRANSPLANTATION AND ADHESION. 



nutritive vessels of the bone is directed are said to heal relatively more readily 

 and more rapidly. 



With reference to the growth and the metabolism of bones a number of in- 

 teresting observations may be recorded: (i) Exceedingly small amounts of phos- 

 phorus or arsenous acid, added to the food, cause marked thickening of the bones. 

 This appears to be due to the fact that the portions of bone that undergo absorp- 

 tion in the process of normal growth for example, the walls of the medullary 

 cavity are not absorbed, but persist, while new growth continues to take place. 

 Small doses of phosphorus are employed for the correction of rachitic softening 

 of bone. In cases of osteomalacia Neumann found an increased elimination of 

 phosphoric acid with the urine. (2) Complete exclusion of lime from the food 

 does not impair the growth of the bones, but makes them thinner, all parts, even 

 the organic matrix of the bone, undergoing uniform atrophy. (3) The ingestion 

 of madder (rubia tinctorum) makes the bones red, the pigment being deposited 

 in the osseous tissue together with the calcium-salts. In birds the egg-shell like- 

 wise is stained. (4) Long-continued administration of lactic acid has a solvent 

 influence upon the osseous tissue. The ashy constituents of the bones are dimin- 

 ished. The changes in the bones in youth induced by the withdrawal of calcium- 

 salts are increased by administration of lactic acid. The bones resemble rachitic 

 bones. Osteomalacia in women can be relieved by castration. (5) Artificial 

 hypostatic hyperemia is capable of increasing the growth of bone. The normal 

 growth of bone is considered in connection with its embryological development. 



At all portions of the body where considerable amounts of tissue have been 

 lost, with secondary inflammation, such defects heal by the formation of a cicatrix 

 of the structure of connective tissue that fills the defect. 



After injury to permanent connective tissue there occurs in the course of 

 three hours an abundant multiplication of the nuclei, which are derived from the 

 matrix, followed by the formation of cells (awakened slumbering cells) , while the 

 fixed connective-tissue corpuscles undergo increase in size. After the formation 

 of the previously slumbering cells from elastic and gelatinous fibers has continued 

 for one or two days, mitotic division is observed particularly early in the cells 

 of the adjacent capillaries, then also in the tissue-cells themselves. This often per- 

 sists for more than eight days. The spindle-cells form blood-vessels, which bridge 

 over the wound-defect, and soon also bundles of fibers, that is, a young cicatrix. 

 The larger the number of cells that become fibers, the firmer becomes the cicatrix; 

 the vessels atrophy and the old cicatrix is firm and deficient in vessels. 



The formative process described occurs in all situations where lost tissue 

 is replaced by connective tissue. On the free surface of the body the newly 

 formed vascular tissue not rarely grows (from wounds and ulcers) above the 

 adjacent level proud flesh. This soon returns, however, to the normal level (after 

 the application of astringents to the vessels), becoming pale, and, finally, after a 

 protecting layer of epidermal cells has developed upon the free surface, forms the 

 cicatrix. 



If the continuity of a tissue has been severed by a wound, as, for example, 

 an incision, the divided surfaces may, after careful apposition, unite directly, 

 without inflammation union by primary intention. The surfaces are at first held 

 together by blood-plasma, and later on direct union of the parts takes place. 

 Divided blood-vessels, however, never reunite to form a blood-channel. The cut 

 surfaces of nerves often unite directly, but direct physiological restoration does 

 not take place. Wherever direct union does not take place, cicatricial connective 

 tissue forms in the sequence of inflammation and suppuration union by secondary 

 intention. 



TRANSPLANTATION AND ADHESION. 



Parts of the body, such as the nose, the ears, and even the fingers, if severed 

 by means of a sharp and clean-cutting surface, may unite, even after the lapse 

 of hours, an evidence that the life of severed tissues may persist for a time. As 

 a matter of fact, some tissues detached from the body may continue to live for 

 a considerable time, for example leukocytes for three weeks, ciliated epithelium 

 for eighteen days. 



The transplantation of flaps of skin is often practised by surgeons to effect 

 closure of existing defects. The flap of skin intended for transplantation, and 

 detached from the subjacent tissues, is permitted to remain for a time attached 

 by means of a pedicle in its original position, and its margins are united accurately 



