294 GEOFFREY JEFFERSON 
it has come about that there should be any antagonism at all 
between the brain and the skull. Antagonism, as will be seen 
below, is practically absent in Prosimiae, but is present to a 
marked degree in man owing to the many new areas he has 
acquired. Hence a better phrase would be ‘evolutionary antag- 
onism’, particularly as there is much evidence to show that the 
human skull and brain are markedly in sympathy, as it were, 
as regards growth in any individual case although the space 
allowed the brain is small. So that ‘growth antagonism’ is a 
misleading term in some respects. It must be remembered that 
there are two integral factors involved in growth antagonism: 
(1) Rapid cortical expansion; (2) Limited intra-cranial space. 
Either of these two factors is capable of profoundly influencing 
the amount of furrow formation and convolution. But it seems 
as if Nature had regulated these factors for each order. As we 
shall see, it seems as if the intra-cranial space was relatively set 
for all the primates, whilst the amount of cortical expansion is 
gradually increased. In other orders different arrangements 
“are made. All histological evidence as embodied in cortical 
maps, supports the fact that the human brain is richer in areas 
than that of any other animal. Difference of histological - 
structure and difference of function seem to be closely allied. 
For as we trace the brains of the animal scale upwards and new 
functions are seen to be acquired we find that the gray matter 
increases in extent, in area, and not in thickness. Brodmann 
has shown that in certain Prosimiae whose brains are poor in 
special areas the amount of cerebral surface to be accommodated 
and the amount of room provided are not much discrepant, so 
that only 7 per cent of the total surface has to be infolded in 
furrows. In the anthropoids so many new areas to house new 
functions have arisen that the discrepancy is much greater, 
whilst in man the quantity of brain surface in excess of the 
accommodation has risen to be two-thirds of the whole (see table 
1). Thus man’s brain is more highly convoluted than that of 
any of the primates, because the increased area of neopallium 
1] refer here to cases of arrested cerebral development and coincident micro- 
cephaly, and the reverse. 
