232 STUDIES IN ELECTRO-PHYSIOLOGY: 



must be fully maintained, if normal conditions are to be 

 preserved. 



Supposing any " faults " to occur, at least three of 

 them should be susceptible to electro -diagnosis 



(1) The drum of the ear may be thickened or overlaid 



by inflamed tissue due to, say, inflammation or 

 rheumatoid conditions. 



(2) The bones of the middle ear may be clogged by 



catarrh, or urates, so that they are not free to 

 vibrate ; or 



(3) The auditory nerve, or line wire, may be faulty. 



In either case the vibrations do not reach the brain 

 unimpaired, because 



(1) They are partly or wholly stopped, or rendered 



" woolly " by the drum. 



(2) If responded to by the drum they fail to set fully 



in motion the clogged bones of the middle ear, 

 or at all ; or 



(2) The faulty line wire fails to carry them fully, or 

 at all, to the brain. 



We have, then, at least three morbid conditions to deal 

 with, and when one of these conditions occurs the telephone 

 system must be tested and the nature and locality of the 

 " fault " ascertained. 



If the drum of the ear is thickened, or the passage to it 

 swollen, by rheumatoid arthritis or other causes con- 

 tributory to local pyrexia, it will yield an abnormal, that 

 is to say a high, deflection. So will the middle ear tested 

 by placing a suitable electrode between the mastoid and 

 the cartilage of the external ear if it is affected by 

 catarrh ; or it will give a subnormal deflection when the 

 bones are, and have been for some time, clogged by urates. 

 In much the same way the inner ear (the line wire) can be 

 made to disclose its degree of conductivity by giving the 



