96 Dr. Dundas Grant [April 27, 



on the top of a walking-stick and walks round the stick several times. 

 He is then suddenly ordered to stand np and walk straight forward. 

 If his labyrinths are normal he cannot do this, and he reels round to 

 the side towards which he has been turning. [This was demonstrated 

 by the lecturer.] If the labyrinths are destroyed, the subject walks 

 straight forward in spite of the rotation. [A soldier whose labyrinths 

 had both been destroyed by specific disease was shown and submitted 

 to this test at the end of the lecture. He was seen to walk straight 

 forward without difficulty.] 



The integrity of the equilibria! labyrinth can thus be tested by 

 rotation or by syringing cold or hot water into the ear. The most 

 convenient means is the blowing in of cold air by means of the 

 lecturer's cold-air lahyrinth-testing apparatus, as used in the French 

 army. 



These tests are important because they indicate the condition of 

 the semicircular canals. If then along with deafness there is 

 evidence of damage at the same time to the semicircular canals, the 

 great probability is that the destruction of the internal ear has been 

 very considerable, that the lesion is a severe one and unlikely to be 

 followed by recovery. 



Simulation of deafness for the purpose of escaping dangerous 

 duty or of securing compensation must be very tempting. It is not 

 surprising that it should occur, but it is very surprising (and credit- 

 able) that it should occur so seldom. There are tests by which it 

 can generally be detected, but their consideration here would " not 

 be in the public interest." 



The frequency with which deafness, either temporary or per- 

 manent, arises in the course of active military service in the field can 

 be only approximately surmised. In a number of our military 

 hospitals about 1 • 4 per cent suffered from some form of deafness. 

 In two German Army Corps 201o cases of disease or injury of the 

 organs of hearing occurred in four months. It is to be remembered 

 that many of the cases were those of ordinary inflammation of the 

 middle ear, apart from injury, incidental to general disease or ex- 

 posure to cold or wet, and that in many the ear-disease was existent, 

 though perhaps quiescent, before enlistment. Professor Moure 

 (Bordeaux) and Professor Lannois (Lyons) have given interesting 

 statistics as to the nature of the disease or injury. The latter gives 

 the results of his observations and treatment in 1000 cases under his 

 care between March and December, 1015, as follows : — 



1. Cases with existent ear-disease -, 323 



(189 had suppuration, 134 had not.) 



2. Cases without existing ear-disease G45 



(262 simple concussion of labyrinth ; 383 concussion of 

 labyrinth with rupture of membrane, in which 

 301 suppurated and 82 did not.) 



3. Cases of deafness from " shell-shock " 32 



