134 



Scientific Proceedings (83). 



may be somewhat different. 1 The symptoms in lower forms per- 

 sist for a longer time. The question arises as to the mechanism 

 of the compensation for the injury in higher mammals. 



The experiments reported in this paper show that the mechan- 

 ism for compensation involves the cerebral hemispheres. 



The experiments were conducted with young cats except in 

 one case in which a fully grown animal was used. The otic 

 labyrinth was removed under asepsis according to the method 

 described by Wilson and Pike. 2 At various periods following the 

 labyrinthine operation, at a time when all ocular and equilibrium 

 disturbances had disappeared, the animals were decerebrated by 

 section of the brain stem just anterior to the corpora quadri- 

 gemina. 



In view of their uniformity a general description of the results 

 will suffice. 



I. The effect of complete decerebration on the position of the eyes 

 in animals which have fully recovered from the ocular symptoms re- 

 sulting from unilateral removal of the labyrinth. 



In all experiments the ocular movements were absolutely 

 normal at the end of three days following removal of the labyrinth. 

 At the end of 3, 11, 12, 16, and 24 days after the labyrinthine 

 operation the animals were decerebrated. This operation was 

 followed by an intense deviation of the eyes to the side of the 

 labyrinthine lesion. The degree of deviation of the eye on the 

 side of the intact labyrinth was somewhat less marked. The 

 deviation of the eyes, as far as could be determined from the nature 

 of the experiments, is permanent. That pure deviation and not 

 nystagmus recurs on decerebration is readily explained by the 

 observations of Wilson and Pike. 2 These author found that the 

 quick return phase is dependent on the integrity of nervous paths 

 in the region of the cerebrum. 



II. The recurrence of disturbances of equilibrium following com- 

 plete decerebration in animals which have fully recovered from the 

 symptoms resulting from unilateral removal of the labyrinth. 



The animals were untied and observed for several hours after 



1 Prince, American Journal of Physiology, 1917, XLII, p. 308. 



5 Wilson and Pike, XVIIth International Congress of Medicine, London, 1913, 

 Section XVI, Otology, p. 563; Arch. Int. Med., 19 15, XV, 31; Proc. Soc. Exp. 

 Biol, and Med., 1917, XIV, p. 75. 



