918 
can be stimulated also by certain kinds of motion (centrifugal force, 
inhibition in rapid progressive motions). 
Finally some microphotos are reproduced for the further elucida- 
tion of the above. 
Guinea-pig 2. 
After the. centrifugation of this animal the following clinical diagnosis was 
made: All the labyrinth reflexes were present in a normal state. As, before 
the centrifugation, the animal turned its head to the left when held up by 
the pelvis with the head downwards, it had to be assumed that the right 
utriculus had functioned before the centrifugation rather more than the left 
one. After the centrifugation no further difference in the functioning of the 
two utriculus otolithes was found, so that it seemed probable that the right 
utriculus had been injured by the centrifugation. Further it had to be expected 
that all the otolithes, as also the semi-circular canals, were intact. 
The histological examination revealed the following facts: 
Semt-circular canals with cristae normal. 
Right sacculus (Fig. 2a.) quite intact. The photo shows the right 
sacculus greatly magnified; the sensory epithelium with the intact otolith 
membrane can be seen. 
Left sacculus (Fig. 2b.) also quite intact. In the photo the intact otolith 
membrane can be seen slightly magnified. 
Right utriculus (Fig. 2c.), as was to be expected, was partly injured. 
In the photo the otolith membrane can be seen in the region of the greatest 
lesion, the part of the membrane that is turned towards the semi-circular 
canals is still lying normally upon the sensory epithelium, the other portion 
of the membrane has been torn off from the sensory epithelium. 
Left utriculus. (Fig. 2d.) quite intact. In the photo the sensory 
epithelium can be seen covered by the normal otolith membrane. 
Thus we see complete accordance between the clinical and the 
pathologic-anatomical diagnoses. 
Cavia 8. 
In this animal it appeared after the centrifugation that all the labyrinth 
reflexes upon motion, i.e. the reactions and after-reactions of head and eyes 
upon rotatory movements and the reactions upon progressive motion, were 
present in the normal way, whereas the tonic labyrinth reflexes were all 
lacking (tonic labyrinth reflexes on the muscles of the body, “Labyrinthstell- 
reflexe”’ and compensatory positions of the eye). 
The clinical diagnosis was as follows: 
Semi-circular canals with ampullae intact; otolithes all tossed off. 
Histologically the following was found: 
Right sacculus (Fig. 8a.): The otolith membrane proved to be entirely 
tossed off. In the photo the sensory epithelium can be seen slightly magnified 
without otolith membrane, while the torn off membrane can be seen in the 
corner of the sacculus. 
Left sacculus (Fig. 8b. and 8c): In fig. 8b the sensory epithelium of 
the left sacculus can be seen more strongly magnified. Nothing is left of an 
