CORTICAL LOCALISATION 293 
times the size that it is at present if man were to have a smooth 
brain, and would necessitate a head so much heavier that the 
whole skeleton would have to be remodelled to support it. The 
figures just given show the immense importance of growth 
antagonism as a causative factor in the production of the cere- 
bral furrows. But growth antagonism between the expanding 
cortex and its fibro-osseous capsule is not sufficient in itself to 
account for the whole story of furrow formation in the primate 
brain, in which the furrows on the whole are remarkably con- 
stant. Ifthe formation of sulci depended alone on the crumpling 
of a plastic surface to accommodate itself to a limited space, 
the furrows so formed would be not necessarily the same in any 
two brains. The constancy of position, length, inclination, 
and direction, of the cerebral sulci of man and the anthropoids 
denotes a mode of origin less fortuitous than this. 
It is evident, then, that the necessity for the appearance of 
furrows at all arises from growth antagonism, but we must look 
to architectural changes in the gray matter as the guiding 
influence in the placing of the furrows. It is of course true 
that the edges of the areas and the sulci do not always corre- 
spond with mathematical precision. On the other hand, the 
remarkably close relationship between the two is one of the most 
striking facts that the cortical maps have brought out. Until 
comparatively recently the furrows were taught to students 
with great zeal as more important than the gyri. We now real- 
ize that the two are causally interdependent. When we have 
more cortical maps, so that an average can be taken and bound- 
aries finally decided upon, it may well be that we shall be able 
to map out the various areas free-hand from the sulci alone. 
This is to a large extent possible to-day, as in the case of motor, 
sensory, visual and parietal areas. 
GROWTH ANTAGONISM 
This is a phrase which needs some explanation. Literally 
it means antagonism between (in this case) a rapidly expanding 
cortex and its limiting capsule. But we shall not be viewing 
it in the proper perspective unless we attempt to realize how 
