Vertigo. Megrims. Blind Staggers. 73 



of the body on its axis toward the injured side. The passage of 

 a galvanic current through the head betiveen the mastoid pro- 

 cesses, or from one external auditory meatus to the other, causes 

 rolHng of the eyeballs. Injection of zvater violently into a rabbit' s 

 ear, or of iced ivater or of a rhigolene jet, causes rolling of the 

 eyes, and rotation of the body toward the side operated on. Dr. 

 Weir Mitchell had a similar experience in his own person. If 

 the injections are repeated a permanent vertiginous condition is 

 induced, and tlie rabbit or Guinea pig, which has been kept 

 in darkness for a few hours and is then suddenly exposed to sun- 

 light, is unstable on its limbs for a few seconds. Lucae found 

 that with perforation of the membrana tympani, an car air 

 douche, at o.i atmospheres caused abduction of the eyeball, 

 dyplopia, giddiness, sense of darkness, and disturbed respiration. 

 Vulpain found that a 25 per cent, solution of chloral hydrate 

 dropped into the ear of a rabbit caused vertiginous movements. 

 McVey records the case of a music teacher who had intense ver- 

 tigo induced by the loiv bass notes of a piano. Crum Brown 

 noticed that if a per.son with bandaged eyes, is rotated for some 

 time as on a potter's wheel, he can at first estimate the degree of 

 rotation, but after a time he fails to do so, and the rotation ma}' 

 be sto])ped, without checking his sense of whirling. The 

 familiar method of subduing an intractable or vicious horse by 

 r'tinning liim rapidly around in a very narrozv circular course, 

 or by tying head and tail together and letting him circle around 

 until he staggers or falls, is another manifest example of this 

 aural vertigo. Rabbits and dogs suffering from acariasis of the 

 external ear move around in a circle, or even turn somersaults 

 tending toward the affected side. Trasbot has found larvae of 

 insects (simulium cinereum?) in the ears of vertiginous horses, 

 which he successfully treated with injection of chloroform. Even 

 hard pellets of wax pressing on the tympanic membrane have 

 been found to give rise to vertigo. 



The explanation of cases of aural vertigo, has been sought in 

 the physiological action of the endoljanph and perilymph on the 

 end filaments of the nerve in the membranous labyrinth, the 

 turning of the head from one side to the other having the effect 

 of changing the pressure in different parts and establishing cur- 

 rents by which the change of position is recognized ; on the 



