PHYSICAL DIAGNOSIS OF THE LUNGS 



121 



on the diaphragm. It is only when the respiration is obstructed that the 

 assistance of the muscles of respiration is required in expiration. The 

 works on physiology give more minute details on this subject. The nor- 

 mal respirations are from twelve to twenty-eight per minute, the size and 



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^ a 



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hi M 



U5 53 



age of the animal making a slight difference, in the smaller dog, of course, 

 being more f rec[uent. Various conditions tend to alter the above number, 

 such as running, physical excitement, atmospheric temperature, the pres- 

 ence of a stranger, particularly if they handle the animal, overloading of 



