PAIN 465 



4. PAIN 



If too strong a stimulus be applied to the skin or if it be continued too 

 long or be repeated too often, a peculiarly disagreeable sensation, which we 

 call pain, is aroused. With a sufficiently strong stimulus the sensation is 

 diffused in our perception more or less beyond the part of the skin directly 

 excited. And from pain of very great intensity convulsions, loss of conscious- 

 ness, or even mental derangement may result. 



Sensations of pain, whose important function it is to direct our attention 

 to all kinds of influences, which, if neglected, might bring us into great 

 danger, are mediated not by the skin alone, but by all other parts of the 

 body as well. Pathological processes in the internal organs of the body or in 

 its members are often accompanied by pain. Cramps of the muscles give rise 

 to severe pains, and the feeling of great fatigue in the muscles after severe 

 work lies on the borderland of painful sensations. Pressure on the eye causes 

 pain, a bitterly cold wind causes pain. Then there are toothache, earache, 

 headache, labor pains, and many others of which we have no need to be 

 reminded. 



It is very difficult to draw a sharp line between actual pain and a mere feel- 

 ing of displeasure. High tones, e. g., are extremely unpleasant ; so also are 

 vibrations and rapid variations in the intensity of light; bad-smelling and 

 bad-tasting substances produce nausea. Several of these and other analogous 

 sensations produce in certain individuals effects quite similar to those of pro- 

 nounced pains. 



Only the painful sensations aroused by the skin have been subjected to 

 exact analysis. 



The cutaneous pains are not always of the same character, but exhibit 

 differences which are due mainly to different combinations of the various 

 sensations mediated by the skin, but also to the extent and duration of the 

 stimulus. Thus a burning pain is accompanied by a sensation of heat; in 

 a stinging pain the disturbance is confined to a small area of the skin; we 

 call a pain cutting if it is distributed over some extent of the body with a 

 certain speed; a throbbing pain is aroused when the pain comes and goes 

 with the pulse, as, e. g., in the case of inflammatory pains, where the pulsa- 

 tions cause an increase in the pressure of the tissue. 



Pain, more than any other sensation, has immediate reference to oneself, 

 and likewise the intensity of pain more than that of any other sensation is 

 influenced by the mind. When a person cuts himself accidentally with a 

 knife, the cut produces no pain worth mentioning even though the wound 

 be a deep one. But let him know beforehand that a slight operation, be it 

 nothing more than a prick of the finger for a blood count, is to be performed 

 on him, and it may cause him real agony. From this it follows that the 

 imagination of pain increases its intensity very greatly. 



By directing the attention very intently to a certain part of the body, a per- 

 son may evoke creeping sensations, sensations of tension, pressure, etc., due to 

 the dilatation of the arteries with the cardiac systole, to pressure of the clothes, 

 etc., which otherwise he would not be conscious of at all, and by continued atten- 



