PAPERS ON PSYCHOLOGY AND PHYSIOLOGY 123 



brain. Some years later, Flourens noted that the same 

 Idnd of behavior resulted from excitation of the cerebell- 

 um and of the semicircular canals.- In spite of the- 

 orists ^-ho have variously conjectured that the canals 

 are the end-organs for the appreciation of time and space, 

 or for noise, or for apprehending the direction of sound, 

 evidence has gradually accumulated that the inner ear 

 does contain an end-organ which is non-acoustical in func- 

 tion and ^vhich seems to be closely related to the mainter- 

 nance of organic equilibrium. In the early seventies 

 Mach. a physicist, Breuer, a physiologist, and Cnmi 

 Brown, a chemist, came independently to the conclusion 

 that the end-ogans in the membranous labyiinth were set 

 into function by the inertia of the liquid enclosing them 

 and enclosed by them. These men supposed that a flow 

 was induced within the canals by foi*ward and backward 

 or rotational movements of the head which excited the 

 end-organs of the vestibular nerve. 



During the latter part of the nineteenth century nearly 

 300 experimental investigations were made on all kinds 

 of animals and upon normal and pathological human sub- 

 jects.^ Rotational, theiTnal. chemical, mechanical, surgi- 

 cal and galvanic means were used to excite the canals, 

 and a brilliant technique led to sound scientific discussion. 

 Most of these studies have confirmed the opinion that the 

 canals are closely related to the maintenance of position. 

 It has not been established, however, that the canals con- 

 tain the sole end-organs of equilibration, the evidence in- 

 dicating rather that the maintenance of position is the 

 product of a large number of factors. 



Xow chief among the organic and mental effects re- 

 sulting from stimulation of the canals, or of one branch 

 of the A^IIth nerve, or of the cerebellum, are certain 

 ocular effects known as nystagmus. Investigators were 

 not slow to suggest that these ocular movements, consist- 

 ing of a slow movement of the eves to the right or the 



2 The best account of Flourens' work is found in his "Recherches es- 

 perimentales sur les propri^tes et les functions du systeme nerveux," 

 Bailliere. Paris. 1S42, pp. 438-501. His experimental work, however, began 

 in 1825. 



* See Griffith. C. R., "A historical survey of the mechanisms of equili- 

 bration," to be published in the Psychological Review, Monog. Series, 1920 



