ARCHITECTURE. 205 



almost exactly one-third is found on the exposed surface 

 of the hemispheres, while the other two-thirds form the 

 walls of the fissures. It is evident from this that other 

 things being equal, the increase in the total length of 

 the fissures would indicate an increase in the cortical 

 extension. The relation of the area which is exposed 

 to that which is sunken is shown in Fig. 38. 



FIG. 38. Diagram illustrating the extent of the cerebral cortex. 

 The outer square shows a surface one-twenty-fifth of 2,352 sq. 

 cm. in extent. The inner square has two-thirds of this area, 

 and is the proportion of the cortex sunken in the fissures. 

 2,352 sq. cm. is approximately the area of the entire cortex in 

 a male brain weighing 1,360 grms. 



The actual total area, say 2,352 cm., is something more 

 than one-fifth of a square meter. The diagram is one- 

 twenty-fifth of the actual area represented by 2,352 

 sq. cm. The inner square has two-thirds of the area 

 of the outer one, so that the space between the outlines 

 of the two squares represents one-third of the area 01 



