THICK WIND. — BEOKEN WIND. 267 



tubes hh, that as the former increases in quantity within the 

 air-passages, the latter, being highly elastic, will necessarily 

 increase in volume; and also, that anything which impedes 

 this free expansion will be attended with proportionate distress 

 to the animal. It will also be evident, that if any foreign 

 agent should by accident or otherwise become fixed between 

 the outer surfaces of the lungs cc, and the inner surfaces of 

 their investing membranes dd, that according to the volume of 

 this agent and its power of resistance, the expansion of the 

 lungs will to a corresponding extent be prevented. Now this 

 is precisely what occurs in Broken Wind. The walls of one or 

 more of the inumerable air-cells or air-passages within the 

 lungs are injured, either from over- distention or from disease ; 

 and the consequence is that air escapes, and is confined between 

 the outer surface of the lungs and their investing membrane dd, 

 and this air not being allowed to return, or to escape in any 

 other direction, presses upon the air-cells below, and by so doing 

 narrows their calibre — thus preventing the organs from ex- 

 panding to that extent necessary to the health and comfort of 

 the animal. It is the presence of air between the hmgs and the 

 pleura pulmonalis which constitutes Umphysema, and which 

 alone constitutes Broken Wind. 



Numerous causes of a permanent nature, and many of 

 them of an obscure character, occasionally give rise to difficulty 

 of breathing ; and very learned veterinary writers endeavour to 

 show that Broken "Wind is dependant upon them, and write 

 volumes of losh to prove it ; but true Broken Wind, we repeat' 

 is dependant upon Emphysema of the Lungs. 



Symptoms. — The symptoms of Broken Wind are— difficulty 

 of breathing ; the respirations are performed not only more 

 frequently in a given time, but the respiratory act is difierently 



