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the eyes of the model were placed in the corresponding position, so 
that now the lengths of the 6 eye-muscles for these various positions 
of the eyes could be measured. 
In the experiments made before, three rotations had always been 
performed. Rotation I. 
Tbe animal originally in ventral-position with horizontal mouth- 
opening, Rotation of the animal round the bitemporal axis, direction 
of the rotation head downwards and tail upwards. 
Rotation II. . 
The animal originally in ventral position, with horizontal mouth- 
opening. Rotation of the animal round the occipital-caudal axis. 
Direction of the rotation: Right eye downwards. 
Rotation III. 
The animal originally in side position, left side downward, right 
eye upward, vertical mouth-opening. Rotation of the animal round 
the venter-dorsal axis. Direction of the rotation: muzzle downwards. 
For each rotation the position of the eyes was stated accurately 
after every 15°. 
The result of the measurements of the lengths of the eye-muscles of the 
model for the various positions of the eyes was stated in tabular form. 
However, the publication of these tabular statements must be put 
off for the moment, as some correction appeared to be necessary. 
For when the eye, starting from the normal position, performs 
rotations, unaccompanied by vertical movements, these rotations of the 
eye-ball cause the points of insertion of the rectal eye-muscles on 
the bulb to be removed, by which the length of the rectal eye- 
muscles is changed passively. 
However, when a rotatory movement combines with a vertical 
deviation of the eye, the contraction of the rectal eye-muscles does 
not take place with the length of those muscles of the normal 
position of the eye, but with the length they have got by (after) the 
rotation (contractions of the oblique eye-muscles). So when the eye 
has performed rotation the lengths of the eye-muscles must be 
rectified with a value, in accordance with the passive lengthening 
or shortening, caused by the contraction of the oblique eye-muscles. 
At the same time, of course, the lengths of the m.m. oblique at 
different vertical deviations should be rectified with a value, in 
accordance with the passive lengthening or shorting of those muscles 
caused by the contraction of the rectal eye-muscles. 
With the help of the model it was easy enough now, by first 
putting the eye in the normal position and stimulating either rotatory 
movements or vertical deviations of the eye-ball exclusively, to 
