ARCHITECTURE. 2OI 



cell-bodies the extent of the cerebral cortex is mainly 

 dependent, while to the associating fibres is due the 

 mass of underlying white substance. A brain possessed 

 of an extensive cortex the elements of which are incom- 

 pletely associated, can therefore be a much folded brain, 

 because the layer of substance forming the cortex is so 

 extensive that in order to have it applied to the surface 

 of the cerebrum it must be thrown into many gyri. On 

 the other hand, the development of the associating 

 fibres, increasing as it does the central mass of the 

 white substance, gives a larger surface to which the 

 cortex may be applied, and in so far tends to diminish 

 its folds. 



The significance of fissuration as an index of intelli- 

 gence receives no support from comparative anatomy, 

 since the brains of ruminants are much more convo- 

 luted than those of the dog, while the heavier and 

 more intelligent birds have brains that are nearly 

 smooth. As has been suggested the fissuration of 

 the brain surface depends upon several variables, and 

 the problem must first be simplified by analysis before 

 a general conclusion is attempted. Precisely at this 

 point, failure to recognise the complexity of the 

 anatomical conditions involved has led to some 

 doubtful inferences. It has been asserted by those 

 most interested in the study of the brains of criminals, 

 that these brains were theromorphic in their surface 

 markings, that is, showed a similarity in this respect to 

 the lower animals, especially the carnivora. This would 

 imply that such brains had been arrested at some early 

 stage. But since the human brain in the course of its 

 development does not pass through a carnivorous phase, 

 it follows that any such peculiarities are fictitious. 1 It has 



1 Cunningham, Contribution to the Surface Anatomy of the 

 Cerebral Hemispheres, Dublin, 1892. 



