722 
At first we supposed that, when e.g. the nystagmus of the left 
eye on douching the left meatus was directed anteriorly upwards 
in ventral position, and posteriorly-downwards with the head down, 
there would be an intermediate position in which there would be 
no nystagmus at all. In other words, if the nystagmus in ventral 
position is Owing to an ampullo-fugal stream in the horizontal semi- 
circular canal, and the nystagmus with the head down to an 
ampullo-petal stream, there would be no difference in the level of 
ampulla and of that portion of the semicircular canal that is cooled 
down by the douche and the nystagmus would consequently not 
appear. This proved not to be the case. True, in this reasoning the 
possibility has been eliminated of an influence of the cold water on 
the lymph-streams in the vertical semi-circular canals. 
Considering that, although also the vertical canals may come into 
play, the horizontal canals are on account of their anatomic loca- 
tion, most exposed to the influence of the cold water, it could be 
anticipated on the ground of Barany’s theory that in the transition 
from ampullo-fugal to ampullo-petal stream in the horizontal canals, 
there would exist a short zone in which, with a slight variation 
in the position of the head, a marked change in the direction of 
the nystagmus would manifest itself abruptly. The critical point at 
which neither ampullo-fugal, nor ampullo-petal streams occur in the 
horizontal canals, so that only streams in the vertical canals can 
exert an influence here, receives a full discussion below. 
Now when looking at the corrected figures, which illustrate the 
mean result of our experiments with the several rotations, the 
following observations can be made: 
a. Rotation I. Douche of the right ear. 
Observation right eye. With the animal in ventral position the 
nystagmus is anteriorly upwards. At 20° (i.e. head 20° below the 
Fig. 5. 
