NECROSIS. 175 



destruction of the medulla is sufficient to cause tlie death of a 

 bone, and it has also been carefully noted that the power of 

 reproduction varies in the different bones of the body, being 

 great in some, and less in others, and in some absent altogether. 

 Thus the long bones, the lower jaw, and scapula possess the 

 power of reproduction to a great extent ; the cuboid and other 

 short bones cannot be reproduced. 



Portions of the cranium, under particular circumstances, says 

 Pirrie, may to a certain extent be reproduced; but if both 

 tables be destroyed, together with the pericranium, there will 

 be very slight reproduction ; for the dura mater has very little 

 tendency to produce new bone, and for this reason reproduction 

 does not take place after the operation of trephining the skull. 

 The bones of the face, however, seem to have the property, for 

 in several instances I have witnessed complete reproduction after 

 trephining the maxillary sinuses. 



SUBPERIOSTEAL SUPPURATION. 



Suppuration beneath the periosteum is not uncommon, and 

 may result from blows, such as " speedy-cut," or from such opera- 

 tions as " punching " for bone-spavin. The symptoms of this 

 form of suppuration are, diffuse swelling, extending in every 

 direction from the seat of injury. The swelling is tense and 

 drum-like when felt ; it may be large, whilst it contains 

 but little pus ; after a time, however, abscesses form on various 

 parts of it, and discharge a foetid pus. The animal is very 

 lame, and a high state of irritative fever supervenes, which 

 may run on to a fatal termination. The treatment for cases of 

 subperiosteal suppuration must be prompt, and should consist 

 in making free incisions through- the periosteum, and thus give 

 vent to the pus. 



Punctured wounds, more especially in the neighbourhood of 

 the elbow-joint, are very apt to be complicated by a collection 

 of pus under the periostum, which, if not allowed to escape by 

 free incision, is apt to burrow upwards into the articulation, 

 thus causing that dreaded complication, open joint. I have 

 seen wounds that were several inches from the articulation 

 terminate in this way. 



