130 JoUKNAL OF COMPAKATIVK NeUKOI.OGY. 



fibres, from which several tracts arise. For this bundle the 

 name " fasciculus internus" is proposed. 



Central tract of the diencephalon (Plate XV, Fig. 10). — 

 One of the most conspicuous tracts of the diencephalon is 

 one passing from the caudad extremity of the fasciculus in- 

 ternus to the central nidulus of the diencephalon. Bellonci 

 has christened this fasciculus the " central tract of the dien- 

 cephalon.'' At one place, near the ventral surface of the 

 mesencephalon, this tract becomes tangent to the external 

 optic tract. At another place it is tangent to the tract pass- 

 ing to the inferior commissure. 



Connecting the central nidulus of the diencephalon and 

 the corpus geniculatum externus, there is a definite tract. 

 This tract is quite short, and lies near the ventral surface of 

 the brain. Histologically, this tract consists partly of fibres 

 and partly of cells. 



Proscnccphalic tract of the corpus gcniculatnvi externum. 

 — From the cephalad (Plate XV, Fig. 11) and mesad (Plate 

 XIV, Fig. 13) surfaces of the external geniculate body arise 

 a number of fibres. These unite into a definite tract, which 

 passes caudo-laterad into the prosencephalon. After enter- 

 ing the crura cerebri these fibres fuse with the peduncular 

 tracts. This renders it difiiult to say which portion of the 

 cortex is supplied by this tract. 



Tract from the mesencephalon to the metencephalon ( Plate 

 XIV, Fig. 10; Plate XV, Fig. 10). — From the caudad portion 

 of the fasciculus internus a well-difterentiated tract passes 

 from the mesencephalon to an ellijosoidal nidulus in the 

 metencephalon. This cell cluster lies near one of the niduli 

 of the fifth nerve. 



IVact to the frosencephalon (Plate XIV, Fig. 10). — 

 Another small tract arises within the mesencephalon, and, 

 curving around the mesad portion of the corpus geniculatum 

 externum, passes cephalo-laterad into the prosencephalon. 



Anterior peduncle of the epcnccphalon (Plate XI\', Fig. 7). 

 — This tract passes cephalo-ventrad from the epencephalon 



