CONTACT CEPTORS 85 



a fall; and the respirations increased in frequency 

 and became irregular. These responses are identical 

 with those which follow the crushing or burning of the 

 hand of a conscious human being. 



Injuries to the muscles of the trunk and extremities 

 caused a rise in blood-pressure similar to that caused 

 by cutting the skin. The rise was more marked when 

 the muscles most exposed to attack were injured 

 such as the muscles of the extremities and abdomen 

 and was less marked when the protected deep lumbar 

 muscles were injured. When amputating the hip of 

 a dog, the skin incision alone caused almost as much 

 change in the circulation and respiration as was caused 

 by severing the entire muscular mass of the thigh. The 

 cutting, burning and tearing of connective tissues 

 fascia, tendons and ligaments produced little or 

 no appreciable effect on the blood-pressure. 



Injury of the bone disclosed the fact that roughly 

 cutting or separating the periosteum caused a slight 

 rise in blood-pressure, while no alteration in blood-pres- 

 sure or respiration was produced by sawing, curetting, 

 cutting or crushing cartilage or bones from which the 

 periosteum had previously been removed. In the fact 

 that injury to the interior of either the large or the 

 small joints is likewise attended by little or no re- 

 sponse, we have seemingly a curious inconsistency. 

 It might be explained on the ground that a crippled 

 animal would have scant chance for life in the wilds. 

 His superior foes would certainly overpower him 

 speedily, so that there would be no opportunity for 

 the development through survival of a protective 

 mechanism. 



