307 



tlie lymj)h, becoming- vascular, is soon transformed into cartilaginous, 

 and in duo time into bony tissue. 



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

 ments is divisible into tAvo distinct jieriods. In the first they are sur- 

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

 by a bony plug or stopper, constituting the period of the provisional 

 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 

 attain sufficient fineness of consistency' for the careful use of the limb 

 witliin 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 

 apparatus from the limb. 



This in general terms represents the fact when the resources of 

 nature 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 i)art 

 of the practitioner, and esx)ecially when, from any cause, the bony 

 fragments have not been kept in a state df x^erfect immobility and the 

 constant friction has prevented the osseous union of the two portions. 

 Failures and misfortunes are always more than possible, and instead 

 of a solid and practicable bony union the sequel of the accident is 

 sometimes a /aZse JO /«^, composed of mere flexible cartilage, a poor 

 pseudartlirosis. The explanation of this appears to be that, first, 

 the sharp edges of the ends of tlie bone disappear hj becoming 

 rounded at their extremities 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 becoming truly ossified, is 

 changed into a sort of fibro-cartilaginous pouch or capsular sac, in 

 which a somewhat albuminous secretion, or pseudo-synovia, permits 

 the movement to take place. Most commonly, however, in our ani- 

 mals, the union of the bonj- fragments is obtained wholly through 

 the medium of a layer of fibrous tissue, and it is because the union 

 has been accomplished by a ligamentous formation only that motion 

 becomes practicable. 



The j)rognosis in a case of fracture in an animal is one of the gravest 

 vital import to the patient, and therefore of serious i)ecuniary concern 

 to his owner. The X)eriod has not long elapsed when to have received 

 siich a hurt was quite equivalent to undergoing a sentence of death 

 for the suffering animal, and j)erhaps to-day a similar verdict is iiro- 

 nounced \i\ many cases in which the exercise of a little mechanical 

 ingenuity, Avith a due amount of careful nursing, might secure a 

 contrary result and insure the return of the patient to his former 



