418 Heterotopia of the White Matter in the MeduUa Oblongata 



system are rare enough to be of interest no matter what their situation, 

 but this bundle is perhaps unusually interesting inasmuch as it seems 

 to form an additional proof of the truth of Hoche's researches on the 



Fig. 1. 



Fig. 2. 



presence of centrifugal fibres in the lemniscus medialis. These fibres 

 were described by Flechsig as receiving their medullary sheaths after 

 birth, long after the larger number of fibres in the lemniscus medialis 

 had become medullated, but our knowledge of their real nature is due 

 to Hoche. In his study of two eases of descending degeneration from 

 unilateral softening he found degenerated fibres, which high up in the 

 pons were distinct from the lemniscus medialis, which then entered 

 the lemniscus and passed down within it as far as the upper end of the 

 nucleus nervi facialis, then becoming separated from the lemniscus 

 these fibres passed, some to the nucleus of the same side, some to the 

 .nucleus of the opposite side. According to Hoche, these fibres as they 

 leave the internal capsule come to lie in the peduncle lateral to the 

 pyramidal tracts. They can be easily traced in his drawings made from 

 Marchi sections, running into the lemniscus medialis and forming there, 

 not a compact bundle, but many scattered bundles, corresponding ex- 

 actly to the non-medullated fibres in the lemniscus of the new-born, as 

 shown by Flechsig. Thus it seems that there are centrifugal fibres in 

 the lemniscus medialis, some of which pass to the nucleus nervi facialis. 

 In my case it would seem that some of these centrifugal fibres became 

 separated on one side and ran as a distinct bundle, dorsal to the lem- 

 niscus, to terminate in the nucleus of the facial nerve on the same side. 

 I can find no evidence, however, of a crossing of any of the fibres, indeed 

 the bundle is throughout very compact. 



