520 
The constancy of the field of vision with different positions of the 
head is owing to tonie labyrinth-, and cervical refleves combined and 
not to tonic labyrinth-reflexes alone. 
When the head is turned on the occipito-nasal axis, such combi- 
nations of labyrinth-, and cervical reflexes will occur, whereas on 
turning the head from the normal position on the dorso-ventral axis 
only cervical reflexes appear. | 
SUI hy 
1. In the rabbit the state of the tonus of the eye-muscles appears 
to depend on the position of the head; the same has previously 
been demonstrated for the skeletal muscles by WHILAND. 
2. The reflexes which control this tonicity can be divided into 
two groups: tonic labyrinth reflexes and tonic cervical reflexes. 
3. The tonic labyrinth reflexes can be examined separately by 
bringing the head into various positions in space; it is required 
that, throughout the experiment, the position of the head relative 
to the trunk does not change. 
4. The fixed laws governing the tonic labyrinth reflexes, were 
published formerly in Pfiiger’s Archiv. (v. p. Honve and Ds KreryN, 
Dr KreyN and Maarus). 
5. The cervical reflexes can be examined separately by bringing 
the trunk into various positions relative to the head or conversely 
the head into various positions relative to the trunk. This experiment 
can only be carried out with animals with both labyrinths extirpated, 
so that tonic labyrinth reflexes are precluded. 
6. For the isolated cervical reflexes the following conclusions were 
arrived at: 
a. To every position of the trunk relative to the head belongs 
a special position of the eyes in the orbita. 
b. In the case of rotations of the trunk about various axes the 
eyes reach their new position in the orbita through various move- 
ments, namely : 
a. through rolling movements when the trunk is turned on its 
frontal axis. Movements of the trunk towards the skull will make 
the eyes roll with the upper pole towards the nose; movement of 
the trunk towards the lower jaw will make the eyes roll with the 
upper pole towards the ear. 
8. When the trunk is turned on its long axis, through vertical 
movements, in which process the eye towards which the back of 
the animal is turned goes downwards, the other goes upwards. 
