92 LOCALIZED ELECTRIZATION. 



The solid metallic rlieophores act energetically upon the sen- 

 sibility of the face, even with a slight current. They actively 

 stimulate the skin of the trunk ; but they are often powerless on 

 the palms of the hands and the soles of the feet, whatever the 

 intensity of the current. 



The metallic threads triple the power of faradization upon the 

 cutaneous sensibility ; and are almost always the only agents 

 capable of exciting it acutely on the palms of the hands and 

 the soles of the feet, in profound anaesthesia of these regions. 



The sensations produced by these several methods of faradization 

 are different. On the face the electric hand produces the effect of 

 a rough brush tearing the skin ; and the metallic threads exert a 

 deeper action. When they are kept stationary, the sensation is 

 like that of hot needles piercing the tissues. The fustigation by 

 threads produces a sensation that differs from this only in its 

 duration. No other agent, not even fire, produces pain equal to 

 that caused by metallic threads ; if we may judge from the state- 

 ments of patients who have also experienced the moxa and trans- 

 . current cauterization. It is very difficult exactly to express these 

 different sensations, and I have striven to do so by using the 

 terms habitually employed for the pur^iose by patients themselves. 



In the normal condition, the cutaneous excitability by electricity 

 differs greatly in different parts of the body. It is necessary, in 

 order to use faradization successfully in cutaneous anaesthesia or 

 in various lesions of tactile sensibility, to know the differences, in 

 this respect, between various regions in the healthy state. 



The skin of the face is indebted to the fifth pair of nerves for 

 exquisite sensibility, and its electric excitability is so great that 

 the most feeble faradic current produces an acute sensation ; even 

 when its effect is scarcely appreciable on other parts of the body. 

 The skin of the face is more sensitive to electric action near the 

 middle line than elsewhere; thus its sensitiveness is greater on 

 the eyelids, the nose, and the chin, than on the cheeks. The skin 

 covering the upper eyelid, the alas and point of the nose, the 

 borders of the nostrils, the sub-nasal depression of the upper lip, 

 and the line of junction of the labial skin and mucous membrane, 

 are the points on which the electric excitation is felt the most 

 acutely. 



On the forehead the sensibility is less than on the face, and still 

 diminishes as the hairy scalp is approached. In the latter it is 

 comparatively slight ; and is only excited by a tolerably powerful 

 current. 



The sensibility is notably greater on the neck and trunk than on 

 the limbs ; in the cervical and lumbar regions than in other parts 



