402 



HITCHCOCK'S ANATOMY 



ity, that one blind man became a botanist, another a con- 

 chologist, and another a land surveyor, simply by the aid of 

 touch. 



738. Effect of Habit on Location of Sensation. — ' 



Habit has a wonderful power in the location of sensations on 

 the skin. Thus it is frequently the case, after an amputation of 

 a limb, that the patient declares that he feels pain in the re- 

 moved portion. This is owing to some irritation in a fiber or 

 fibers of the remaining nerve trunk, which were originally 

 sent to the supposed seat of the pain, and from habit the suf- 

 ferer locates it in the removed part. Also after the Talia- 

 cotian operation — which consists in making a new nose from 

 the skin of the forehead, — if the nose itches, the patient 

 scratches the forehead as the seat of the irritation. 



739. Insensibility produced by a long continued 

 Action of some painful Stimulus. — It is sometimes the 

 case that the nerves are rendered insensible by the moderate 

 but long continued action of some painful stimulus. A com- 

 plete insensibility of the skin may be produced, so that the 

 severest surgical operations may be performed without pain, 

 by the application of snow and salt mixed in equal portions. 

 Heat will also do the same thing, as shown by the following 

 example. " A traveling man one winter's evening laid him- 

 self down upon the platform of a lime kiln, placing his feet, 

 probably benumbed by the cold, upon the heap of stones 

 newly put on to burn through the night. Sleep overcame 

 him in this situation : the fire gradually rising and increasing, 

 until it ignited the stones upon which his feet were placed. 

 Lulled by the warmth the man slept on ; the fire increased 

 until it burned one foot and part of the leg above the ancle 

 entirely off, consuming that part so effectually that a cinder- 

 like fragment was alone remaining, and still the wretch slept 

 on, and in this state was found by the kiln man in the morn- 



738. What effect has habit upon localizing our sensations ? 739. How may insensibility 

 be sometimes brought about ? What wonderful example ? 



