50 RESTORATION OF FRACTURED BONES. 



of the membrane, which presents a fleshy appearance, in con- 

 sequence of a sort of gelatinous infiltration. The effused blood 

 becomes absorbed, and a ropy, viscous, gelatinous fluid, is 

 poured out between the ends of the fragments, which is essential 

 to the production of the permanent callus. 



The second period extends from the tenth or twelfth, to the 

 twentieth or twenty-fifth day. During this period, the engorge- 

 ment of the surrounding parts, diminishes and the muscles are 

 liberated : but the cellular tissue remains condensed and con- 

 centrated round the fracture, presenting grooves or even canals 

 to the tendons of the muscles if any pass in the vicinity of the 

 fracture, in which they are able to play, though with little free- 

 dom, in consequence of some existing induration of the cellular 

 tissue. This constitutes the provisional callus, the external 

 portion of which is thickest at the place of fracture, and insensibly 

 terminates upon the fragments of bone. Its internal portion is 

 formed by the periosteum, which is closely attached to the bone. 

 Its structure is whitish, homogeneous, and of a cartilaginous or 

 fibro-cartilaginous character. The medullary membrane forms a 

 similar plug of provisional cartilaginous matter, which fills up the 

 whole cavity of the bone, above and below the place of fracture. 

 The viscous or gelatinous fluid interposed between the ends of 

 the bones, is now rose-colored or red, presents sometimes a floc- 

 culent appearance, and is adherent by its margins to the external 

 and internal callus. The limb may still be bent at the place of 

 fracture, but no crepitation can be produced. 

 The third period extends from the twentieth or twenty-fifth 

 day, to the thirtieth, fortieth or sixtieth, according to the age 

 and health of the patient. 



Ossification commences in the centre of the cartilage, and by 

 degrees the whole tumor, internal and external, becomes os- 

 seous. It is very vascular, and Howship* has succeeded in 

 injecting the vessels. If at this period the bone be cut longitu- 

 dinally, the provisional callus will be found presenting all the 

 characters of spongy bone, while the fragments will be found 



* Microscop. Observ. 



