623 



In this phase of compensation extirpation, or a squirt of cold water 

 into the other ear maj' excite nystagmns. If a squirt of cold water 

 into tlie ear is equivalent to elimination of t[je labyrinth on the 

 same side, then both labyrinths will have been eliminated in case, 

 in the compensatory stage, the unimpaired ear is irrigated. It 

 follows then that the nature, the direction or the frequency of the 

 forthcoming nystagmus can no more be modified by altering the 

 animal's position in space. 



d. A concomitant flow of water into the two ears, generally brings 

 forth a condition in which no nystagmus manifests itself. If therefore, 

 squirting cold water into the labyrinth is identical with elimination, 

 •a concomitant flow into the tw^o ears cannot provoke a rotatory 

 movement or a deviation of the eyes in case the animal's position 

 in space is altered. > 



These phenomena have been examined in the following way : 

 Ad. a. In order to ascertain whether the caloric nystagmus (which 

 term here always indicates the nystagmus occurring after squirting 

 water, of from 11° — 12°, into the animal's ear from a height 

 of 1,5 m.) corresponds completely to the spontaneous nystagmus 

 occurring after unilateral extirpation of the labyrinth, a number of 

 experiments were undertaken. In these experiments the animals (in 

 this series only cats) were tied to an operation board and subse- 

 quently the caloric nystagmus was examined in 6 different positions 

 of the animal : 



1 ventral position. 



2 dorsal position. 



3 vertical position, head up. 



■4 vertical position, head down. 



5 lateral position, the irrigated ear up. 



6. lateral position, the irrigated ear down. 



After this the labyrinth on_ the side of the irrigated ear was 

 extirpated. The technique of this operation has been described by 

 one of us in another paper. M After the animal recovered from the 

 narcosis, the nystagmus was again examined in the six positions 

 just mentioned. With some aninials the examination was repeated 

 the next day. We noted the frequency, the direction and the nature 

 of the nystagmus. The frequency of the nystagmus cannot be 

 accurately demonstrated in these experiments, it being apt to change 

 every moment as well in the spontaneous nystagmus as in the 

 caloric nystagmus. We are entirely ignorant of the cause of it. 



') Pfiügers Archiv. Bd. 145 p. 549. 



