( 299 ) 



principal nucleus has assuredly lost fibres, especially in the portion 

 situated caudal of the hearth. Such is likewise the case with the 

 "Gitterschicht", although it is no where louched directly by the 

 hearth. In the neighbourhood of this latter a great number of' the 

 fibres passing the Gitterschicht in their course from the thalamus 

 towards the retro-lenticular portion of the capsula interna, are dege- 

 nerated. Those degenerated fibres gather into an area, lying close to 

 the "Gitterschicht", an area, which in preparations made after 

 Weigert-Pal's method, contrasts with its surroundings by its being 

 light coloured, against the black coloured retro-lenticular portion of 

 capsula. (see fig. IVa) s ). 



Situated at first lateral of the "Gitterschicht" (see tig. IVa), 

 this area may be pursued caudalwanl (fig. [Va, fig. Va x a 3 , fig. Vla^a^a,) 

 and frontalward (fig. Illa^ and tig. IIa 3 ). In the caudal sections its 

 ventral boundary is the medullary triangle surrounding the corpus 

 geniculatum externum ( W in fig. Ill), expanding thence both in the 

 stratum sagittale externum and in the stratum sagittale internum 

 (see fig. Ill and fig. IVj. In frontal sections this field is situated in 

 the capsula interna, medialward from the caudal ending of the 

 putamen nuclei lenticularis (fig. IIa s ). 



This degenerated area may be followed in three directions: 

 1 st in the medullary rays of three temporal convolutions (see 

 tig. I— VllaJ least in the gyrus temporalis I, 



2 nd in the splenium corposis callosi (see fig. VI and VIIa 8 ) 

 3 rd in the medullary rays of' the gyrus supramarginalis and still 

 for a large part in the gyrus centralis posterior (see fig. I — \Tlrt 2 ). 

 When examined in glycerine preparations the medulla of these gyri 

 is thickly interspersed with granular cells. 



Summing up the abovetold facts, we find some definite distur- 

 bances of perception in an old woman, after a lesion produced by 

 a hearth of degeneration strictly localized within the left thalamus. 

 These disturbances are : 



1 st Temporary deafness on both sides, leaving as its stationary 

 result a certain degree of dullness of hearing on both sides. 



2'" 1 On the right side a chronic loss of sensibility in all qualities 

 of sense of the skin and the deeper-situated parts, almost complete 

 in the distal ends of the extremities, less marked in the trunk and 

 in the roots of the extremities, unimportant in the face. All this is 

 not accompanied by any choreic movements on that side, whilst 

 there is found only a very slight ataxy to the right. 



2 ) In the drawings the areas arc represented too light-coloured. 



20 



Proceedings Royal Acad. Amsterdam. Vul. XI. 



