October iSlh, igio.] Proceedings. 



Ordinary Meeting, October i8th, 1910. 



The President, Mr. Francis Jones, M.Sc, F.R.S.E., 

 in the Chair. 



The thanks ot" the members were voted to the donors of the 

 books upon the tables. 



Professor G. Elliot Smith, M.A., M.D., F.R.S., read a 

 paper entitled, "The Convolutions of the Brain." 



It is well known that in a series of mammals belonging to 

 the same family, the cerebral cortex is more extensive in the 

 larger animals ; but the increase in the extent of the cortex does 

 not remain proportionate to the bulk of the creature, because 

 the size of the cerebral cortex is determined by the area of the 

 sensory surfaces of the body which are relativety smaller in the 

 larger animal. 



It is also well known that, in order that the blood vessels 

 may convey to the cortex an abundant supply of nutriment, 

 and, at the same time, cause a minimum amount of mechanical 

 disturbance, the cortex does not increase in thickness to any 

 extent, so that every addition to its bulk is expressed wholly in 

 the expansion of its superficial area. It follows that in passing 

 from the small smooth-brained members of any mammalian 

 family to its larger representatives, the cortex must become 

 folded in order to be packed in the limited area provided by 

 the surface of the brain. 



It has now become possible to explain the nature of the 

 factors which determine and guide the process 01 folding rendered 

 necessary by these known fundamental conditions. 



In all mammals special parts of the cortex become cultivated 

 by each of the senses — one area is set apart to act as a receptive 

 and recording apparatus for impressions of sight, another for 

 hearing, another for touch, another for smell, and so on. In the 

 more highly organised mammals other areas become differentiated 



