JJ02 



tlie R side. Perhaps other cerebellar symptoms would have come 

 more to the fore-gromid when a different combination had been made. 



II. In my previous report ') I came to the conclusion that, as 

 sensory cerebellar ataxia must arise through interruption of the 

 afferent, extero- and pi-oprioceptive equilibrium tracts in the cere- 

 bellum, this ataxia naturally will appear, when those parts of the 

 cerebellum are affected, where these fibres are found. 



The consequence is that where the parade-step can be evoked 

 ^.r/rrt-cerebellar, and this symptom also is derived /?i^/Y/-cerebellar, 

 a field of the cortex must be destroyed in which these afferent 

 fibres end. 



Now it is well-known that the tiactus spino-cerebellaris dorsalis 

 (Flechsig) ends in the cortex of the vermis, and the tract us spino- 

 cerebellaris ventialis (Gower) in the vernis superior and the nuclei 

 tecti. From this follows, that all the important afferent tracts from 

 the medulla spinalis and from the vestibular organ are only in con- 

 nection with the vermis and the above mentioned nuclei. 



Previous experiments '•') which I made proved however, that the 

 paradestep appears after removal of pai-ls of the cortex of the lob. 

 paramedianus, lying laterally from the vermis. 



These two facts therefore do not agree and the (piestion arises, 

 whether an explanation is to be found for this. Directly three pos- 

 sibilities come to the fore ground. The first is that my investigations 

 were not propeily made. Against this I wotdd say, that in ten dogs, 

 larger and smaller parts from the lobulus paramedianus were cut 

 out and that in seven dogs the parade-step was found, while this 

 dysmetria in the gait did not appear in any of my other animals. 

 Therefore it is likely, that the right localisation was obtained. 



The second is, that the view is not right, that the mentioned 

 afferent tracts should oidy end in the vermis, but that they possibly 

 also pass into more latei-ally lying parts of the cortex. Against this 

 can be advanced, that a gi-eat number of investigators have proved, 

 that the mentioned ti-acts do not end outside the vermis. This 

 fact too may be taken for certain. 



The third explanation could be, that one has in the cerebellum 

 correlations, wdiicli histologically are not yet brought to clearness 

 and through wiiich the afferent im[)ulses, arrived at the vermis, are 

 projected towards other parts of the cerebellutn. 



In this report I will not go deeper into the last question, which 

 to me seems the most probable, as more special investigations will 



1) Verslag Kon. Akad. v. Wet. Januari 1918. 



2) Psych. Neurol, bl. 1909. 



