J 84 THE FARM DOCTOR. 



complication is met The air rushes from the tubes of the 

 lacerated lung into the pleural cavity during each inspiration, 

 and as it cannot find its way back, the whole of that half of 

 the chest is soon filled with air and the lung compressed into a 

 small solid mass attached to the lower end of the windpipe, and 

 opposite the base of the heart. The lesion is thus liable to 

 prove fatal, though if arrested early by the exudation of lymph 

 in the wound of the lung, the air may be absorbed, and 

 recovery may ensue. 



WOUNDS PENETRATING THE CHEST. 



Whether connected with broken ribs or only involving the 

 muscles between the ribs, these lead to the accumulation of air 

 in the chest and collapse of the lung, as when a broken rib has 

 torn the lung tissue. The edges of the wound, having been 

 driven in, act like a valve, allowing the entrance of air during 

 the expansion of the chest, but forbidding its escape when that 

 cavity collapses. It is far more serious than the accumulation 

 of air in the chest from a torn lung, as decomposition and irri- 

 tation are set up by the presence of germs which are filtered 

 out in passing through the lungs. Unless the wound is small 

 and can be closed early, it is necessarily fatal. 



SHOULDER LAMENESS. 



The lameness which accompanies injuries to the shoulders 

 may be so characteristic as to be recognised at a glance. The 

 specific features are, the carrying of the head low; the dragging 

 of the toe on the ground in advancing the limb ; the swinging 

 of the foot outward so as to describe the arc of a circle in 

 bringing it forward; and, if severe enough, the standing with 

 Joints partly bent, the heel raised, and the toe resting on the 

 ground, but without any advance of the lame foot in front of 

 the other. 



