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bring about a union by the first intention, and in another tlie work will 

 be accompanied by suppuration, or the union by the second intention, 

 a process so familiar in the repair of the soft structures by granulation. 



Considering the process in its simplest form, in a case in which it 

 advances without intfrruption or complication to a favorable result it 

 may probably be correctly described in this wise : 



On the occurrence of the injury an effusion of blood takes place be- 

 tween the ends of the bone. The coagulation of the fluid soon follows, 

 and this, after a few days, undergoes absorption. There is then an 

 excess of inflammation in the surrounding structure, which soon spreads 

 to the bony tissue, when a true ostitis is established, and the compact 

 tissue of the bone becomes the seat of a new vascular organization, and 

 of a certain exudation of plastic lymph, appearing between the peri- 

 osteum and the external surface of the bone, as well as on the inner 

 side of the medullary cavity. After a few days the ends of the bone 

 thus surrounded by this exudate become involved in it, and the lymph, 

 becoming vascular, is soon transformed into cartilaginous, and in due 

 time into bony tissue. 



Thus the time required for the consolidation of the fractured seg- 

 ments is divisible into two distinct periods. In the first they are sur- 

 rounded by an external bony ring, and the medullary cavity is closed 

 by a bony plug or stopper, constituting the period o( the proinsional 

 callus. This is followed by the period of permanent callus, during which 

 the process is going forward of converting the cartilaginous into the 

 osseous form. 



The restorative process is sooner completed in the carnivorous than 

 in the herbivorous tribes. In the former the temporary callus may at- 

 tain sufQcient fineness of consistency for the careful use of the limb 

 within four weeks, but with the latter a period of from six weeks to two 

 months is not too long to allow before removing the supporting appa- 

 ratus from the limb. 



This in general terms represents the fact when the resources of na- 

 ture have not been thwarted by untoward accidents, such as a want of 

 vigor in the constitution of the patient or a lack of skill on the part of 

 the practitioner, and especially when, from any cause, the bouy frag- 

 ments have not been kept in a state of perfect immobility and the con- 

 stant friction has prevented the osseous union of the two i)ortions. Fail- 

 ures and misfortunes are always more than possible, and instead of a 

 solid and practicable bony union the sequel of theaccidentis sometimes 

 a false joint, composed of mere flexible cartilage, a poor pseudo- arthrosis. 

 The explanation of this appears to be that, first, the sharp edges of the 

 ends of the bone disaj^pear by becoming rounded at their extremeties by 

 friction and j)olishing against each other. Then follows an exudation 

 of a plastic nature which becomes transformed into a cartilaginous layer 

 of a rough articular aspect. In this bony nuclei soon appear, and the 

 lymph secreted between the segments thus transformed, instead of be- 



