341 



In the second group we bring the cases, where there was 

 possibly some lesion of the N. vestibularis, recognisable by a less 

 compact degeneration in that nerve and certainly not caused by a 

 direct lesion, but by an indirect one as shifting of the cranial contents, 

 vicinity of an malacial hearth and also by retrograde degeneration. 

 In this it strikes us, that the N. Vestibularis appears not only to 

 be exposed to an associate lesion after an operation in the posterior 

 cerebral cavity, but that also the \'ulnerability of this cerebral nerve 

 is observed after lesions of some distant structure. 



We have to stand still with the three cases (107, '108, 109) where 

 the region of the posterior commissure was wounded. 



In these cases the forced movements cannot be considered as 

 having the same origin. In cat 108 the dependence of the rolling 

 and circus movement to the left on the degeneration found in the 

 vestibulary nerve is most conspicuous, because in this case no degene- 

 ration in the secondary vestibulary system was found. On the other 

 hand we find in 107 a slight, even doubtful, degeneration in the 

 L. vestibulary nerve, which cannot be considered responsible for the 

 long lasting circus movement to the R. nor for the long lasting 

 rolling movement to the h. As we saw in a former publication ^) 

 the descending degeneration of the most medial segment of the 

 P, L. B. on the operated side is most common'') in animals, where 

 a lesion of the region of the posterior commissure was performed 

 and circus movement ensued to the operated side. 



5'or some time I considered the rolling movements to the L. dependent 

 on the centrifugal degeneration of the bundle, lateral to the P. L. B. 

 (Probst)^) particularly because also one of Karplus and Economo's^) 

 animals had shown after a similar lesion rolling movement (and the 

 position in that sense) to the normal side; equally in this animal 

 this bundle was found degenerated. 



Later experience however leads me lo doubt whether this bundle 

 has anything to do with the forced movements. Also regarding the 

 bundle that degenerates within the area of the P. L. B. from the 

 interstitial nucleus far down the spinal cord (interstitio-spinal bundle) 

 I am not in the position to deny nor to affirm its relation to the 

 vestibulary system, and physiologically spoken to the forced mo\e- 

 ments. The fact, that in 2 cats (107 and 108), which performed 



1) Gomp. Transactions Royal Dutch Academy 26 Oct. 1912 p. 727. 

 ') Compare Boyce. Neurologisches Genlralblatt. 1894. p. 467. 

 ^) Jahrbücher fur Psysichiatrie und Neurologie 1903. Vol. 23. p. 1 7 and Deutsche 

 Zeitschr. L Nervenheilk. 190Ü. Vol. 17. p. 156. 

 ^j Archiv fur Psychiali-ie Vol. 46 page 393. 



