Chap. XXIII.] OF THE HUMAN BRAIN. 441 



of the Hemispheres.* These two sets of fibres do not 

 proceed to the grey matter of the Convolutions separately, 

 but are for the most part inextricably mixed with those 

 fibres of the Peduncle (above referred to) which pass unin- 

 terruptedly through the Central Ganglia. Outside these 

 bodies, moreover, all three sets of fibres become further 

 intermixed with those of the great transverse commissure 

 between the hemispheres — the Corpus Callosum. 



But some further account must be given of the course 

 of these three sets of fibres — answering to the * projection 

 system ' of Meynert. Their mode of distribution is neces- 

 sarily a matter of great importance, if any coherent notions 

 are to be formed even as to the simpler modes of action 

 of the Brain. The reader ought, therefore, carefully to 

 study the particulars given below, making, as he proceeds, 

 frequent references to those figures in which the relative 

 position of the Convolutions alluded to may be seen. The 

 substance of Broadbent's description is subjoined. f 



The fibres of Cms, Thalamus, and Corpus Striatum always run, 

 more or less, in company with one another to the same parts. For 

 brevity, they may be spoken of as ' radiating ' fibres. 



(But, wherever ' radiating ' fibres go, thither also go fibres of Cor- 

 pus Callosum — though not necessarily in the same proportion. Thus 

 it happens, that those Convolutions in which ' radiating ' fibres ter- 

 minate or commence, are also bilaterally associated through the 

 Corpus Callosum, and are thereby fitted for conjoint activity.) 



These ' radiating ' and ' callosal ' fibres are not distributed 

 equally to all the Convolutions. Many of the latter do not receive 

 a smgle fibre from Crus, Thalamus, Corpus Striatum, or Corpus 

 Callosum, but have only an indirect communication with the ceu- 



■5^ Broadbent says (" Journ. of Ment. Science," Ap. 1870, p. 9) : — 

 "A comparison again, of the sectional area of the fibres thus seen 

 issuing from the Central Ganglia with the area of the Crus as it 

 emerges from under the Pons, will show that the ascending fibres 

 have been largely reinforced by additions from the Ganglia." 



t " Brit. Med. Journ.," April 8, 1876, p. 433. 



