517 
LIL. Combination of labyrinth- and cervical reflexes. 
When discussing the tonic labyrinth- and cervical reflexes sepa- 
rately we saw in both cases that when the head is brought from 
one position into another, the eyes make an effort to retain their 
position im space. 
It also appeared that this could neither be attained by the tonic 
labyrinth reflexes nor by the cervical reflexes, much less even by 
the latter than by the former. 
Now the question arises what a combination of labyrinth-, and 
cervical reflexes can bring about. Quantitative results in this research 
will be best afforded by eye-positions occurring when in a vertical 
plane the head is brought into different positions relative to the 
trunk (i.e. by raising and lowering the head). 
As said above, with a fixed trunk the tonic labyrinth reflexes 
can be examined alone by fixing the head also and by bringing the 
whole animal (so the head also) into different positions in space, in 
which process tonic cervical reflexes are precluded in consequence 
of the fixed position of the head relative to the trunk throughout 
the experiment. By changing the positions of the head relative to 
the trunk also tonic cervical reflexes can be examined separately, 
but then only with animals in which through previous bilateral 
extirpation of the labyrinths tonic labyrinth reflexes have been 
eliminated. 
When, bowever, of normal animals the head is brought into 
different positions relative to the trunk, we shall observe tonic laby- 
rinth reflexes because the position of the head in space changes, 
as well as tonic cervical reflexes, because the position of the head 
relative to the trunk is changed. 
This is shown in Fig. 3. 
After cocainization a cross is burned into the cornea. A little 
window is placed before the eye, as in our experiments on tonic 
labyrinth reflexes in conjunction with v. p. Horve. The rotatory 
movements can be established directly by taking a photograph of 
the eye with the window before it. 
In the curve 1 mm — 1° rotation. 
Fig. 3. The full line indicates the rotatory movements at the 
raising and the lowering of the head. 
The dotted line indicates the rotatory movements for the tonic 
labyrinth reflexes alone, determined in the way previously described 
with v. p. Hoeve. The hatched field shows the rotations for which 
the cervical reflexes alone are responsible. 
