132 FLORENCE R. SABIN 



has been removed and some of the dorsal-lateral nucleus and 

 pulvinar have been cut away. The extent of the ventro-lateral 

 nucleus is best estimated in fig. 4, from which it has been entirely- 

 removed, the fibre mass, consisting of the knee of the internal 

 capsule and external medullated lamina on the ventro-lateral 

 aspect, and the posterior limb of the internal capsule on the lateral 

 surface, making a shell in which the nucleus rests. The ventro- 

 lateral nucleus is separated from a dorsal nucleus, which is the 

 dorso-lateral nucleus and pulvinar together, by a band of non- 

 medullated fibres which is plain in the newborn (see no 57, figs. 

 5 and 7), but not at all sharp in the adult (see fig. 8), on account 

 of the great number of medullated fibres. In fig. 8, the ventro- 

 lateral nucleus and the combined dorso-lateral nucleus and pul- 

 vinar are imperfectly separated, by the fact that there are more 

 medullated fibres in the ventro-lateral nucleus than in the dorsal 

 mass. As has been described, the ventro-lateral nucleus has two 

 sets of medullated fibres at birth, sfirst the bundle from the medial 

 lemniscus (no. 18), which enters the caudal part of the nucleus, 

 near the median plane just ventral to the center median of Luys. 

 A part of this bundle spreads out in the external medullated 

 lamina. Secondly, the medullated cortical bundle (no. 26) emerges 

 from the extreme lateral surface of the nucleus and helps make 

 up the cortical radiation. 



The dorso-lateral nucleus of the thalamus (no. 58), cannot in 

 any way be separated from the pulvinar (no. 51). These two nu- 

 clei make a common mass of cells as can be well seen in fig. 5, the 

 term pulvinar being simply used for the caudal part of the mass. 

 Far to the side, as seen in fig. 3, the dorsal mass of the thalamus 

 is less extensive, inasmuch as it lies wholly dorsal to the center 

 median of Luys, than it is near the median plane, as can be seen 

 in fig. 5, in which it lies not only dorsal to the center median of 

 Luys but anterior to it as well. In fig. 3 it will be readily under- 

 stood that the part labelled 58, and indicated by striation, is the 

 cut surface of the dorso-lateral nucleus, the part which fits over 

 the oblique surface of the ventro-lateral nucleus having been cut 

 away. Thus the ventro-lateral nucleus is bounded on its median 

 surface partly by the median nucleus and partly by the dorso- 



