CONTACT CEPTORS 83 



the injured part. In previous books and papers 1 it has 

 been shown that unconsciousness produced by inhalation 

 anesthesia does not interfere with certain discharges of 

 energy in response to physical injury, and that, except 

 for the absence of pain and muscular action, the ulti- 

 mate effect of trauma under anesthesia is the same as if 

 the injury were inflicted upon a conscious animal. In 

 other words, with the exception of the diminished or ab- 

 sent response of the skeletal muscles, the reaction of an 

 anesthetized animal to a certain degree of trauma is 

 comparable to the reactions of a conscious animal to the 

 same trauma. This reaction includes an increased re- 

 spiratory and heart rate, a disturbance of the blood- 

 pressure, an increased acidity of the blood and the urine 

 and if the injury inflicted be sufficiently great his- 

 tological changes in the brain, the liver and the adrenals. 

 Since in some degree all the physiological phenomena 

 above enumerated attend upon every activation, any 

 one of them may be taken as an index of the entire proc- 

 ess. In our investigation of the effect of mechanical 

 injury upon various parts of the body the blood-pres- 

 sure and the respiratory rate were taken as an index. 

 That is to say, if injury to the paw of a dog caused a rise 

 in blood pressure and increased respiration, these 

 changes were regarded as indices of the total stimula- 

 tion, and as an evidence of the existence of pain ceptors 

 in the part producing the response. 2 If on trauma- 

 tizing a given region no change in blood-pressure or 



1 G. W. Crile : An Experimental and Clinical Research into 

 Surgical Shock ; G. W. Crile and W. E. Lower : Anoci Association. 



2 In the abdominal region a fall, not a rise, in blood pressure 

 occurs. If trauma causes any change in the blood-pressure, whether 

 it be a fall or a rise, the presence of contact ceptors is indicated. 



