FRACTURES OF BONES. 147 



absorption. Between the tenth or twelfth to the twentieth or 

 twenty-fifth day an exudation of Ivniph takes place, the repara- 

 tive material being deposited between the fractured ends of the 

 bone, and known as the callus. From the twentieth or twenty- 

 fifth day to the .thirtieth, fortieth, or sixtieth day the fibro- 

 cartilage between the periosteum and the bone and that within 

 the medullary canal are both converted into bone, the external 

 forming- a ring and the internal a plug, or peg, filling up the 

 medullary canal, and together constituting the provisional 

 callus. During the fifth and sixth months the callus increases 

 in hardness, from day to day, until it is finally converted into 

 bone, constituting the permanent callus. Extending from the 

 fifth or sixth month to the tenth or twelfth, the provisional 

 callus, being no longer necessary, disappears, and the medullary 

 canal is restored. The reparative material makes the parts as 

 strong, or stronger, than l)efore fracture. 



FRACTURE OF THE HUMERUS. 



Fracture of the humerus is caused by falls, kicks, and severe 

 injuries, such as are sustained sometimes in running away. We 

 are of the opinion that perfect soundness cannot be restored in 

 this fracture. The powerful muscles attached to this bone pull 

 the fractured ends out of place, in spite of any appliance that 

 can be used. A very young animal may be treated when the 

 fracture is known as a simple one; but as a rule it is best to 

 destroy the animal. 



Symptoms. — The fractured ends nre drawn past each other 

 as in the cut. The limb is shortened, the inferior portion of the 

 bone being drawn ui)wards by the muscles attaclied to it; great 

 lameness; crepitus may or may not he well marked. It some- 

 times happens that humeral arteries are ruptured, causing great 

 engorgement of this part of the limb^ and rendering detection 

 of crepitus an impossibility. The condyles of the humerus are 

 occasionally fractured; as a rule^ they never will unite^ because 



