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self-preservation has ceased, and that its vitality is 

 gone. If that tooth be felt, it will, in the majority 

 of instances, be found loose, and therefore it can be 

 easily extracted : the operation, however, is not then 

 ended. Should the affected organ have occupied the 

 upper jaw, a quantity of pus may flow freely into 

 the mouth on its extraction, but more frequently such 

 will not be the case : nevertheless, the discharge 

 from the nostril, (should the case have been of long 

 standing,) together with the softened and swollen 

 condition of the facial bones, may convince the 

 attendant that matter is locked up in the maxillary 

 sinuses. Some writers speak of the antrum as the 

 part most seriously affected ; but I cannot find any 

 thing corresponding to the antrum in the horse's 

 head. That animal has no development of this de- 

 scription, and therefore it only shows ignorance to 

 operate with a special view to opening an imaginary 

 cavity. The maxillary sinuses are spacious cells, 

 and freely communicate with the frontal sinuses, 

 which are also large. These facial sinuses have 

 but a limited and kind of valvular opening into the 

 nasal chambers, and if pus is allowed to remain 

 within them there is little hope of cure : therefore a 



