?A'2 



(hiring- the loiigeyl period rolling movements, tends to throw some 

 doubt on the interpretation, presented above, viz. that the second- 

 ary lesioJi of the vestiDularj roots might alone be responsible for 

 these disturbances. It suggests the possibility, that this interstitio- 

 spiral bundle, descending low down the coi'd, might represent the 

 elferent tract for the rolling movement, as we saw the commissnro- 

 medullarj bundle did for the circusmovements. The vulnerability of 

 the vestibulary nerve to distant lesions renders the analysis, of this 

 sort of functional disturbances viz. rolling in their relation to the 

 anatomical findings extremely delicate. Not only in lesions of, the 

 Mesencephalon and of the Cerebellum but also after a lesion caudal 

 to the exit of the 8"^'' nerve (as in cat J 45) this nerve root may be 

 indirectly hurt. 



These indirect lesions (by shifting of the cranial contents etc.) 

 produce functional disturbances of the same order as those observed 

 after direct lesion of that nerve. This is proved by the fact that 

 practicaly only rolling niovements ensue, which take place towards 

 the side on which the black particles are found, particularly in the 

 fan-like part of the intra-medullary course of the vestibulary nerve, 

 after having passed the narrow passage between the corpus restiforme 

 and the descending 5^^^ Nucleus. It is remarkable that in all cases 

 the indirect vestibulary lesion was found on the contra-lateral side 

 of the primary lesion. 



The duration of the forced movements after indirect vestibulary 

 lesion, is naturally far less than after a primary lesion ^). 



Finally it is interesting to know that in my lesions of the region 

 of the posterior commissure only in 109 some slight degeneration in 

 the lateral part of the Fasciculus DeUers Ascendens (Lkwandowski, 

 Winkler) was found. I think it allowed to infer from this fact that 

 solely in this case also Deiters Nucleus had undergone some secondary 

 changes, of which some black particles in that structure give evidence. 



I also think we may infer that the vestibulary nerve itself is 

 far more vulnerable, than its nuclei and ascending connections, 

 independent of the fact, that - — as I have proved — {he forced 

 mo\'ements (rolling) observed after direct vestibulary lesion are of a 

 far more vehement character than after a lesion of its secondary 

 connections. 



1) It is probable, that in human pathology a good part of the most common 

 symptoms of increased cerebral pressure (dizziness), reflectory disturbances of the 

 oculai' movements, falling sidewards) will prove to be the result of a similar 

 indirect vestibulary lesion, this nerve being after these experimental results far 

 more vulnerable than its secondary iutra-cerebral connections. 



