ORIGINAL ARTICLES 7 



Goll, whilst posteriorly the base of the wedge shows scattered 

 fibres, reaching here and there to the periphery of the cord. As 

 the fibres are traced down the cord into the dorsal region they 

 become more scattered, and, as a result of the giving off of 

 collaterals, thinner ; whilst they pass for the most part towards 

 the posterior periphery of the cord. At the same time, the angle 

 of the tract opens out so that the fibres, now in section, assume 

 that of a wide angle, or even that of a boomerang. 



These fibres had evidently degenerated from at least the upper 

 part of the mesencephalon down to the lower dorsal region. Their 

 path above the decussation of the pyramids will be given in a later 

 communication, in conjunction with some other facts elicited in 

 that research. But the fibres under discussion could be traced in 

 the posterior columns degenerating downwards, and passing into 

 the dorsal region, and in one or two cases traces of similar fibres 

 could be seen actually extending into the lumbar and sacral 

 regions. The specimens, photographs of which are here given, 

 were obtained from the monkey, and a brief note of the fact was 

 sent to the Physiological Society in January last. Since then I 

 have seen, in five or six other cases, fibres similarly degenerated 

 and occupying the same position, though as yet I have not seen 

 them so well marked as represented in the present case, the 

 reason for that being, in all probability, the particular method of 

 operation adopted in the research mentioned above, in which the 

 endeavour was to produce merely a small and limited lesion in 

 the thalamic region or regions. Hence such fibres, if damaged at 

 all, would usually be damaged only in small numbers. 



Further work has been carried out with the view of eluci- 

 dating other points in connection with this particular tract, but 

 it is not yet complete. 



The fibres described above must, of course, be long endo- 

 genous fibres, which have their origin high up in the mid-brain, 

 or even slightly anterior to this, in the thalamic region, and 

 descend as far as the lower dorsal region, or even lower. 

 The fact that the tract diminishes as it descends in the spinal 

 cord, the fibres becoming smaller and more scattered, occupying 

 a fan-shaped area below the upper dorsal region, would show 

 that the fibres are composed of, as is usually the case, short, 

 intermediate and long fibres ; and, as in a somewhat analogous 

 case, that of the posterior longitudinal bundle, it would be 



