913 
b. Rotatory Deviations. 
In the rotatory deviations the relations are much more compli- 
cated than with the tonic labyrinth reflexes hitherto discussed. A 
fuller discussion would, however, claim more space than we have 
at our disposal, for which reason we shall merely mention the 
results which the different considerations have led to. 
The rotatory deviations of the eyes found with the compensatory 
eye positions may perhaps be explained by the following hypothesis. 
The foremost sacculus corners have their own innervation, are bent 
laterally and thereby lie almost in one frontal plane. Each sacculus 
corner has a functional connection with the obliquus sup. and inf. 
of both eyes. When the otolith hangs from the sacculus corner, the 
oblig. sup. of both eyes are the most strongly contracted and the 
obliq. inf. the most relaxed. When the otolith presses upon the 
sacculus corner, it is the obliq. inf. which is most contracted and 
the obliq. sup. most relaxed. As the sacculus corners lie almost in 
the same plane, no distinct change in the position of the maxima 
and minima are to be found after uni-lateral extirpation. As each 
sacculus corner influences the oblig. sup. of both eyes similarly and 
the obliq. inf. reciprocally, the rotatory deviations remain qualita- 
tively unchanged after uni-lateral extirpation, and are reduced quanti- 
tatively to about the half. 
Thus, with the rotatory deviations, it is not clear that the hanging 
otolith exercises the strongest and the pressing otolith the weakest 
stimuli, but it seems as if stimuli, even though opposed, are caused 
by hanging as well as by pressing otoliths. 
SUMMARY. 
By means of a model, constructed in the Anatomical Institute of 
Utrecht, of the otolithes in their correct position in the rabbit-skull, 
an examination has been made as to whether the different tonic 
labyrinth reflexes might be otolith reflexes. Experimentally in all 
tonic labyrinth reflexes the position of the head has been determined, 
whereby these reflexes have their maximum and minimum. The 
following conclusions were arrived at: 
1. The tonic labyrinth reflexes upon the muscles of the body 
proceed from the utriculi. One utriculus macula is connected with 
the muscles of both extremities; but, on the contrary, with the neck 
(and trunk) muscles of one side of the body only. 
2. The ‘Labyrinthstellreflexe” are reflexes of the sacculus. Whether 
the utriculi also play a part is not certain. 
