510 
one position to another, the eye performs such movements to attain 
its new position in the orbita that it, as it were, tries to retain its 
spatial position. The curves in the above-mentioned publication show 
with how little suecess. To this we shall revert later on. 
We still wish to insist emphatically that these tonic reflexes must 
be distinguished from the transient eye-movements which appear 
during or directly after the movement of the head. This distinction 
is often more or less overlooked in the literature. The compensatory — 
eye-positions are determined by tonic reflexes and vary only with the 
position of the head in space. The determined eye-position, therefore, 
continues, until this position of the head in space is changed. 
In all experiments on compensatory eye-movements due care should 
also be taken that during the experiment the position of the head 
relative to the trunk cannot change. 
That in the above researches we really had to do with labyrinth- 
reflexes could be readily proved, as they disappeared completely 
after bilateral labyrinthine extirpation. 
II. Tonic cervical reflexes acting on the eye-muscles. 
Very little is known in the literature about tonic cervical reflexes 
acting on the eye-muscles. BARANY *) is the only author who (in 1907) 
published an investigation which warranted the assumption of such 
reflexes. In experiments on rabbits, the head of the animal being 
fixed and the trunk being moved relatively to the head, round 
different axes, eye-movements were the result. The results, however, 
varied and the reflectory eye-movements also appeared to depend 
on the position of the head in space. Technical difficulties prevented 
him from ascertaining experimentally whether cervical reflexes come 
into play here. 
On a priori grounds it seems to me improbable that true cervical 
reflexes should fundamentally be varying according to the position 
of the head in space. 
The question, therefore, urges itself upon us whether in the case 
of Barany’s reflexes, we may have to do with a superposition of 
cervical and labyrinth reflexes. The same cervical veflexes may very 
well evoke different eye-movements, when these reflexes affect eyes 
which, in consequence of tonic labyrinth reflexes, take up another 
position in the orbita when the position of the head in space is 
altered. 
1) R. Barany. Augenbewegungen durch Thoraxbewegungen ausgelöst. Centralbl. 
f. Physiol. Bd. XX. 
