94 Di\ Dundas Grant [April 27, 



desirable as it was that unnecessary pain should be avoided, and that 

 unnecessary repetitions of experiments should be prevented. He 

 recommended for support the society presided over by Lord 

 Lamington, and expressed a hope that the State or the possessors of 

 wealth would provide for the endowment of research.] 



Fourth. — The auditory centres may be thrown out of par by a 

 nervous shock, the most typical of which is that of being " buried." 

 Many who have undergone this terrifying experience have been deaf 

 and voiceless when dug out. Slighter forms of fright produce this 

 effect in more sensitive subjects. Such loss of hearing unconnected 

 with physical damage to the auditory organs is termed ^'functional " 

 decifness. The higher centres are, as it were, switched off, so that the 

 sufferer is as unconscious of the sensations of sounds as if his internal 

 ear-apparatus was destroyed. The internal ear and auditory nerves 

 are, however, still in working order, and may be stimulated by sounds. 

 This is shown by the occurrence of certain natural movements on 

 exposure to sound even though the subject is quite unconscious of 

 them. These movements are " reflex," and their occurrence indicates 

 that the accompanying deafness is " functional " rather than physical 

 or " organic." Kecovery is usual, and is sometimes quite dramatic in 

 its suddenness, though when and how the recovery is to be brought 

 about it is scarcely possible to predict. As a shock brings it on, 

 sometimes another shock removes it. In one case a fall out of bed 

 led to complete recovery from total deafness of this form. Fright 

 can produce degenerative clianges in nerve-cells (disappearance of 

 Nissl bodies, etc.), as shown in the special (Purkinje's) cells of the 

 cerebellum in Crile's experiments on rabbits in relation to shock. 

 There is also good reason to suppose that the dendrites of the neurons 

 may retract as the result of shock and cause interruption of continuity 

 in the nerve strands leading to the cortex of the brain. Colonel 

 Mott favours the latter view, and in support of its feasibleness quotes 

 Ross Harrison's observations on the growth of nerve processes from 

 cells in the embryo. 



This deafness is analogous to that which may be induced by the 

 so-called mesmerist or hypnotist by means of " suggestion," and is 

 no doubt identical with deafness or other loss of sensation observed in 

 true hysteria. The " conscious " is absent, but the " sub-conscious " 

 is stiir more or less to the fore and open to impressions which the 

 " conscious " would rule out or inhibit when not stupefied by fear or 

 terror. 



Fifth. — Destruction of both auditory cortical centres as the result 

 of wounds would produce deafness, but, of course, such an extensive 

 injury could scarcely be compatible with life. 



Cases frequently occur in which more than one of these factors 

 are present, and we may find associated with " functional " deaf- 

 ness affecting both centres an organic damage to one of the labyrinths. 



Sixth. — Apart from injury, diseases of the ear are the cause of 



