558 THE CEREBRUM. 



they bend downwards within the gyms to which they belong, and are connected 

 with the anterior perforated space, being joined by certain longitudinal fibres which 

 run along the under surface of the corpus callosum near the middle line, passing 

 near and upon the upper edge of the septum lucidum. Behind, they turn round the 

 back of the corpus callosum and thence descend to the point of the middle lobe, where, 

 according to Foville, they again reach the perforated space. Offsets from these fibres 

 pass upwards and backwards into the secondary convolutions derived from the gyrus 

 fornicatus in the longitudinal fissure. 



b. fasciculus uncinat,us. Under this name is described a white bundle, seen on 

 the lower aspect of the hemisphere, passing across the bottom of the Sylvian fissure, 

 and connecting the anterior with the middle and posterior lobes. The fibres of this 

 bundle expand at each extremity, and the more superficial of them are curved or 

 hooked sharply between the contiguous parts of the anterior and middle lobes, 

 whence it has derived its name. 



c. The convolutions of the cerebrum are connected with each other by white 

 fibres, which lie immediately beneath the cortical substance. Some of them pass 

 across the bottom of the suicus between adjacent convolutions ; whilst others, which 

 are longer and run deeper, connect convolutions situated at a greater distance from 

 one another. 



Fig. 381. 



Fig. 381. VIEW OP A DISSECTION OP THE FIBRES OF THE GYROS FORNIOATUS AND FORNIX, 

 IN THE RIGHT HEMISPHERE ^sli^htiy altered from Foville). 4 



A, the anterior lobe ; B, the posterior lobe ; a, a', a", fibres of the gyrus fornicatus ; 

 C, cf, oblique bands of fibres of some of its accessory gyri; b, tegtnentum, and g, crust of 

 the crus cerebri, separated by the locus niger ; I, thalamus ; m, fissure of Sylvius ; n, corpus 

 albicans ; q, median section of the corpus callosum ; s, septum lucidum ; t, the fornix, 

 its anterior pillar descending into the corpus albicans, and then emerging from that at its 

 termination (*) in the thalarnus ; 1, the olfactory bulb ; 2, the optic commissure. 



The researches of Foville have led him to differ considerably from other 

 anatomists as to the course of the fibres of the cerebrum, as will be seen from the 

 following statement of his views. 



1. The crust or fasciculated portion of each cerebral peduncle, derived from the 

 anterior pyramid, forms by itself the peduncular fibrous cone, and is thence con- 

 tinued on into the radiating fibres of the cerebrum, which are destined only for the 

 convolutions on the convex surface of the hemisphere, including the outer half of 

 the marginal convolution of the longitudinal fissure, and the inner half of the con- 

 volution of the Sylvian fissure. 



2. The fibres of the tegmentum, having entered the thalamus, pass on in two ways 

 no part of them, however, joining the radiating peduncular fibres. 



a. One set pass upwards through the thalamus and corpus -triatum, above which 



