Literary Notices. xv 



Breuer called attention to the inertia of the eyeball by which on a sud- 

 den movement of the head the eyeball would be displaced in its orbit, 

 thus interfering with the precision of the visual judgment of the actual 

 angular displacement of the head. The nervous connections with the 

 ampullae are for the purpose of correcting this displacement of the 

 eyeball by the contraction of the appropriate muscles, the latter being 

 reflexly excited by the head movement as registered in the vestibular 

 sense organs. It is movements in the horizontal plane which are chiefly 

 to be compensated and it is a significant fact that it is the abductors 

 and the adductors of the eyeball which are in most intimate connection 

 with the vestibular apparatus. 



The view of Mendel that vertigo is an oculo-motor disturbance is 

 combated ; on the other hand it is regarded as in every case due to an 

 irritation of the connections of the eighth nerve. No doubt titubation 

 can produce vertigo, but the reverse is the rule, and the fact that we 

 see objects oscillating is a sort of reflex titubation of the eyeballs sec- 

 ondarily induced by reason of the intimate relations existing between 

 the muscles of the eyeballs and the vestibular connections. 



Upon the irritation of the labyrinth the abductor of the same side 

 and the adductor of the opposite side are excited and the eye quickly 

 turns toward the side of the irritation ; the elasticity of the opposing 

 muscles returns the eye to its normal position, but more slowly so that 

 the only disturbance of sensation which results is an apparent rotation 

 of the visual field in the direction opposite to the latter motion. In 

 other words objects appear to move toward the side of the irritation. 

 This is a fact which the author has found to be of the greatest value in 

 clinical practice. Vertical nystagmus is very rare. The author has 

 observed two cases of which the origin was purely labyrinthin. The 

 details of several cases of ocular disturbance occasioned by both laby- 

 rinthin and bulbar lesions are given and at the close the author con- 

 cludes: "Ampullar disturbances can find their symptomology in all kinds 

 of oculo-motor disturbances, and in the presence of the latter it should 

 be remembered that after the retina itself it is the labyrinth and par- 

 ticularly the ampullae which are concerned with oculo-motor functions 

 as well as with equilibrium. All of the oculo-motor nidi, with the ex- 

 ception perhaps of that of the oblique, which I have never seen in- 

 volved, may thus be affected by reflex irradiation issuing from the 

 ampullar apparatus." 



These results of Bonnier agree also remarkably well with those ob- 

 tained by Lee in his experiments upon the dog fish (Galeus Cants). 



c. J. H. 



