THE CORPUS CALLOSUM. 537 



regarded as peculiar to phrenology, and as so essentially 

 connected with it, that if the system of Gall and Spurzheim 

 be untrue, this theory cannot be maintained. But it is 

 plain that all the system of phrenology built upon the 

 theory may be false, and the theory itself true ; for the 

 school of Gall and Spurzheim assume, not only this theory, 

 but also that they have determined all the primitive facul- 

 ties of which the mind consists, i.e., all the faculties to 

 which special organs must be assigned, and the places of 

 all those organs in the cerebral hemispheres and the cere- 

 bellum. That this is a system of error there need be no 

 doubt, but it is possibly founded on a true theory : the 

 cerebrum may have many organs, and the mind as many 

 faculties ; but what are the faculties that require separate 

 organs, and where those organs are situate, are subjects 

 of which only the most general and rudimentary know- 

 ledge has been yet attained. 



Of the physiology of the other parts of the brain, little 

 or nothing can be said. 



Of the offices of the corpus cattosum, or great transverse 

 and oblique commissure of the brain, nothing positive is 

 known. But instances in which it was absent, or very 

 deficient, either without any evident mental defect, or with 

 only such as might be ascribed to coincident affections of 

 other parts, make it probable that the office which is com- 

 monly assigned to it, of enabling the two sides of the brain 

 to act in concord, is exercised only in the highest acts of 

 which the mind is capable. And this view- is confirmed 

 by the very late period of its development, and by its 

 absence in all but the placental Mammalia.* 



To the fornix and other commissures no special function 



* See cases of congenital deficiency of the corpus callosum, by Mr. 

 Paget and Mr. Henry in the twenty-ninth and thirty-first volumes of 

 the Medico- Chirurgical Transactions. 



