66 



PHYSIOLOGY 



CHAT. 



assumed great physiological importance. Laiujv was the tirst 

 who considered the pains and cutaneous hyperaesthesia that 

 accompany certain diseases of the internal organs that are little 

 sensitive, or insensitive, to be reflex. Since the work of Eoss 

 (1888), of Mackenzie (1892), and specially the more detailed 



Km. 25. Diagram of zones and areas of hyperalgesia, after the clinical researches of Head. 



Explanation on p. 68. 



observations of Head (1898), the theory of referred pain has 

 acquired great interest, and in view of the modern segmental 

 theory is of marked theoretical importance. 



According to Head, certain morbid conditions of the internal 

 organs are capable of provoking painful sensations, but these 

 are almost always falsely located, i.e. in a part other than 

 that affected. In the diseased organ, too, abnormal sensations 



