EXPANSION OF THE FIBRES INTO THE HEMISPHERES. 583 



commissura mollis of the third ventricle. The corpus stria- 

 turn is cineritious on its upper surface, or that which presents 

 to the ventricle, and is made up in its interior of alternate 

 strata of cineritious and medullary neurine, which gives it 

 when divided vertically a striated appearance, from which it 

 has received its name. The cineritious neurine in both these 

 organs, is marked with white medullary lines, which Gall first 

 described as the origin of new medullary fibres reinforcing 

 those which come from the medulla oblongata, to be expanded 

 into the cerebrum. Hence he assigned to the corpus striatum 

 and thalamus, the names of ganglia of the cerebrum. 

 From all points of the surface of these two ganglia, except 

 those which form the walls of the ventricles, medullary fibres 

 radiate in all directions, forming the solar rays or fan (even- 

 tail) of Vieussens, and the radiating crown of Reil. Many of 

 the fibres which emerge from the thalamus, pass also through 

 a portion of the corpus striatum, and seem bridled, as it were, 

 by the curvilinear band of white fibres called tenia striata which 

 is placed along the inner margin of the corpus striatum. 

 The fundamental point in the anatomy and physiology of 

 the cerebrum, consists in determining the ulterior course of the 

 fibres which radiate from these two ganglia, corpora striata, 

 and thalami optici, in order to constitute the convolutions of 

 the cerebrum, and the various bands which connect the differ- 

 ent parts of the brain together. This has not yet been satis- 

 factorily accomplished. 



Gall and Spurzheim, have considered them as passing off as 

 bundles of diverging rays, in the form of inverted cones, to the 

 outer or cineritious covering of the hemispheres, (hemispherical 

 ganglia,) and that new fibres from the termination of these, or 

 the same reflected inwards, pass subsequently in an opposite 

 direction under the name of converging fibres to form the 

 commissures. Tiedemann and Foville, with at least equal 

 reason, have considered the hemisphere of each side as formed 

 of a layer of medullary fibres, in the form of a sac, the com- 

 mencing point of development of which as seen in the foetus, 

 is at the sides of the corpus striatum and optic thalamus ; the 

 fibres of the sac being covered on its outer face with the gran- 



