504 THE SENSORIAL FUNCTIONS. 



touching the most projecting part of the forehead. 

 Camper conceived that the magnitude of this angle 

 would correctly indicate the size of the brain, as 

 compared with the organs of the principal senses 

 which compose the face ; but the fallacy of this 

 criterion of animal sagacity has been shown in a 

 great many cases. 



<§ 4. Functions of the Brain. 



Physiologists have in all ages sought for an elu- 

 cidation of the functions of the brain by the accu- 

 rate examination of its structure, which evidently 

 consists of a congeries of medullary fibres, ar- 

 ranged in the most intricate manner. Great pains 

 have been bestowed in unravelling the tissue of 

 these fibres, in the hope of discovering some clue 

 to the perplexing labyrinth of its organization ; but 

 nearly all that has been learned from the labo- 

 rious inquiry, is that the fibres of the brain are 

 continuous with those which compose the columns 

 of the spinal cord ; that they are variously inter- 

 mixed with grey neurine, as they are in ganglia, 

 in their course through masses of nervous matter, 

 which appear to be analogous to ganglia ; that 

 their remote extremities extend to the surface of 

 the convolutions of the brain and cerebellum, which 

 are entirely composed of grey neurine : and that 

 these latter portions, again, are connected exten- 

 sively by commissural fibres.* 



* By the application of high magnifying powers Ehrenberg has 

 found that white neurine is composed of very minute fibres of dif- 

 ferent sizes ; the larger being cylindrical tubes, containing a granular 



