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upon different animals; the compensatory eye ‘positions’ only upon 
rabbits and guinea-pigs, as in the case of animals with quick volun- 
tary eye-movements, such as cats and dogs, these reflexes are not 
so well suited for quantitative examination. In the Anatomical Insti- 
tute, Messrs. pe Burrer and Koster kindly determined for us by 
various methods the position of the otolithes in the rabbit head, 
and constructed a model from which, in each position of the head, 
the accompanying position of the otolithes could immediately be 
seen, so that it was now possible to trace whether with the maxima 
and minima of the tonic labyrinth reflexes also a typical position 
of the otolithes was to be met with. This proved to be the case, 
as this paper will further show. 
It was finally desirable to answer the question as to the correct- 
ness of the supposition that the tonic labyrinth reflexes are otolith 
reflexes, and at the same time to investigate whether this is also 
the case with the reactions upon progressive movement, as il is 
fairly generally assumed to be according to the theory of Macu and 
Breuer. For this purpose a method had to be employed whereby 
the influence of the otolithes was in some way eliminated, while 
keeping the semi-circular canals intact. The reflexes of the latter 
should then be present and the otolith reflexes absent. This method 
of control, as will be seen later, also confirmed the presupposed 
function of the otolithes. 
The result of the above-described investigations, shortly summarized, 
was as follows: 
A. PosiTION OF THE OTOLITHES WITH THE DIFFERENT TONIC 
LABYRINTH REFLEXES IN THE RABBIT. 
1. Tonie labyrinth reflexes upon the muscles of the body. 
(Extremities and neck) 
a. On the extremities. 
When the tonus of the muscles of the extremities is examined in 
the various positions of the head, it appears that the extensors attain 
their maximal tonus whenever the head lies symmetrically on the 
skull, the nose making an angle of 0° — 45° upwards (individual 
differences). When the tonus of the extensors is minimal, the posi- 
tion of the head differs from the former by 180°. 
If the model of the rabbit’s skull with its otolithes be now put 
into the same positions, it will appear that with the aforesaid 
maximum and minimum, the utriculus otolithes also have a very 
typical position (the individual variations anatomically found agree 
