ROARING IN HORSES. 75 



rings, the separation of their extremities by 

 retaining the canula too long in the trachea, 

 the pressure exercised on the upper part of 

 that conduit, and the extension of inflam- * 

 mation of the mucous membrane to the 

 perichondrium are the causes of this accident. 

 Partial ossification of the incised rings, of the 

 cricoid, and of the thyroid results in every 

 case ; but it remains limited to the parts 

 of the cartilages which surround the wound 

 and leads to no deformity of the larynx. 



6. Shrinking of the Ti^achea at the Point 

 of Application of the Elastic Balloon. — This 

 follows partial gangrene of the tracheal 

 mucous membrane, and is the result of the 

 pressure exercised on that membrane by 

 the too great distension of the caoutchouc 

 balloon. The fibrous new growth or neo- . 

 plasm, which follows the casting off of the 



