1359 
This was effected in the following way: Tracheotomy was per- 
formed in a rabbit under ether anaesthesia and the respiration was 
maintained artificially. The vagi were severed and the carotids were 
temporarily closed by a clamp. Subsequently the M. externus of 
one eye, say the left one, was prepared and at its extremity a 
thread was attached through which with the aid of a lever the 
contractions of this muscle could be registered on a kymograph. 
Then followed the extirpation of the eyeball. 
Hereafter the skull-cap was removed, likewise the cerebrum and, 
after a frontal section through the brainstem a little before the cor- 
pora quadrigemina, part of the brainstem. Finally section of the 
two N.N. occulomotorii and the two N.N. trochleares at the base 
of the skull, and of the right N.N. abducens- and trigeminus at their 
entry into the orbita. So all the eyemuscle-nerves and consequently 
also all proprioceptive nerves of the eyemuscles were cut through 
with the exception of one N. abducens, whose associated M. externus 
was used for the registration of the nystagmus. 
In some experiments also the two N.N. trigemini were severed 
at their exit from the medulla, with a view to ascertain once more 
whether a normal nystagmus could be evoked after severing both 
trigemini. Of this little is known in the literature. Héegyrs') points 
out that in experiments conducted in his laboratory by Keurtrsz and 
v. Marscuanko, vestibular eye-movements still occurred after section 
of the ganglion Gasseri; however, in his. description he does not 
state clearly whether or no a quick phase came forward. Moreover 
these experiments were made only unilaterally. 
Kuro *) only states in his well-known communication on the ves- 
tibular reflexes in rabbits: “Die Durchtrennung des N. vagus, glos- 
sopharyngeus und trigeminus in der Schädelhöhle bleibt ohne 
Hinfluss auf die Reaktion nach der Einspritzung”’. 
Fig. 1 shows the nystagmus in a rabbit whose M. externus had 
been isolated to the /eft and whose N.N. trigemini, N.N. oculomotorii, 
N.N. trochleares and right N. abducens had been cut through. With 
the contraction of the M. externus the curve ascends. 
From this experiment it appears that deviation and nystagmus 
are still demonstrable after severing both N.N. trigemint and all 
the eyemuscle-nerves with the eaception of one N. abducens by douching 
alternately the two meatus with cold water and registering the 
movements of the still innervated M. externus. When syringing the 
!) Ueber den Nerven mechanismus der assoziierten Augenbewegungen, tibersetzt 
von MARTIN SUGAR. Urban und Schwarzenberg 1918, p. 82. 
2) Pflügers Archiv. 1906. Bd. 114, p. 151. 
88 
Proceedings Roval Acad. Amsterdam. Vol. XXIII. 
