320 



NORMAL HISTOLOGY. 



The outer division, or the putamen, of the nucleus lenticu- 

 laris closely resembles, both in color and in structure, the caudate 

 nucleus, with which, indeed, it anteriorly becomes continuous. The 

 paler color of the inner segments, the globus pallidus, depends 



C.t 1 , 



Section across anterior end of thalamus, striatum, and insular th, anterior end of thalamus ; st.t., 

 stria terminalis; n.c., nucleus caudatus ; n.l., outer segment of nucleus lenticularis ; l.m., l.tn. 1 , ex- 

 ternal and internal medullary lamina receiving fibres (x~) from caudate nucleus ; c.i., internal capsule ; 

 c.f., external capsule; cl, claustrum ; co, cortex of island of Reil ; co.a., anterior commissure; g, 

 central gray matter of third ventricle, a, its commissure; c.f., section of anterior pillar of fornix ; 

 b, c, d, e, elements of subthalamic region ; e 1 , stratum zonale of thalamus ; o, portion of optic tract. 

 (After Schwalbe-Meynert.} 



not only upon the presence of greater numbers of medullated fibres, 

 but also upon the lighter tint of the yellowish pigment contained 

 within the multipolar nerve-cells. The nerve-cells contained within 

 the claustrum are principally fusiform elements whose long 

 axes correspond in direction with the neighboring free surface. 



The optic thalamus is composed chiefly of gray matter, through 

 which extend various tracts of nerve-fibres. The surfaces directed 

 towards the ventricles are sharply defined, the upper or dorsal 

 aspect being covered by a layer of medullated nerve-fibres, the 

 stratum zonale, about .8 mm. in thickness, which fade away on the 

 mesial surface ; the outer and ventral borders of the thalamus, on 

 the contrary, are invaded by fibres from the respectively adjacent 

 internal capsule and the subthalamic region. 



The gray matter of the thalamus is divided by tracts of fibres 

 into a shorter median segment, the inner nucleus, and a longer 



