254 STUDIES IN ELECTRO-PHYSIOLOGY: 



incidental to inflammation, and as a consequence the 

 nervous impulse or current is not conveyed at normal 

 pressure to its destination, to supply blood-vessels, to 

 actuate muscular fibres, or to energise or transmit messages 

 to various cell-groups. 



Nor is this the full extent of the mischief. The current 

 escaping through the fault, in conformity with natural 

 laws, seeks the path of least resistance to earth (air), and 

 from that point throughout that path the cells are in a 

 highly electrified area, and, their insulation not being 

 capable of withstanding the strain, they in all probability 

 become over-ionised. A condition is thus created favour- 

 able to the multiplication of inimical bacteria and 

 unfavourable to phagocytosis. 



The path of least resistance must be from the fault 

 through the intervening tissues and the skin, to air, and 

 generally, it will be the shortest path. But wherever it is 

 it is clear that an abnormal quantity of current must issue 

 from that part of the skin in which the " path " terminates, 

 and that if we place the circular plate upon the centre of 

 the forehead of the patient in order to be sure of getting 

 on the central line, and another electrode upon the affected 

 area both electrodes being, of course, connected to the 

 galvanometer the fault will manifest itself by a more or 

 less rapid excursion of the light upon the scale ; that is to 

 say, the rapidity of the excursion will be proportionate to 

 the quantity of neuro- electricity escaping, and that quan- 

 tity will also be proportionate to the rise of local tempera- 

 ture or to the degree in which local insulation resistance 

 has been broken down by temperature. 



Let us, for example, take a case of lobar pneumonia, 

 the base of the right lung being affected (Fig. 143). 



Here, after taking the hand-to-hand deflection, we are 

 able to make intelligent comparison of the galvanometric 

 readings from the affected and the unaffected lung, or at 



