298 GEOFFREY JEFFERSON 
ence of fabrics. So that when furrows must occur, their position, 
length, and direction are determined by differences of archi- 
tecture in the gray matter. But the depth of the furrows, and 
what is synonymous with this—the amount of cortex buried in 
the sulci, is determined by the amount of growth antagonism 
present. In other words, in the primates furrows are necessarily 
produced because a great number of cortical areas have to be 
housed in a small space and the depth of the furrows will depend 
on the amount of discrepancy between the volume of the occu- 
pier and the space to be occupied. 
It must be remembered that a furrow is not an entity in itself 
any more than dyspepsia is a disease. Both are symptoms— 
the furrow of evolutionary changes in the cortex. It will be 
quite evident in the light of modern knowledge that the much 
discussed (6) temporary furrows are post-mortem artifacts, as 
Hochstetter and Elliot Smith have shown. 
So much for furrow formation in the primates. 
A glance at the accompanying table will reveal a very curious 
fact, that there are brains more rich in sulci and gyri than man’s, 
and this in animals much further removed from him than his 
ancestral primates. Thus certain of the carnivora, ungulates 
and cetacea, have brains distinguished by an extraordinary 
luxuriance of convolution. And it is very confounding at first 
to observe that the elephant, horse, and probably the whale 
(Brodmann) have more convolutions than man. It is impossible 
to concede that the brains of these animals can be so rich in 
areas as many of the lower apes, not to mention man, in spite 
of the so-called sagacity of the elephant, horse and dog. Corti- 
cal maps of these animals are not yet forthcoming,? since atten- 
tion has been very naturally fixed first on the primates. Yet 
the only logical inference that can be drawn in the case of the 
genera now under discussion is that furrow formation in their 
case must depend on factors different from those just laid down 
for the primates. And since cortical specialisation has pre- 
sumably not reached a high point in them, we must look to the 
2 Brodmann refers to surveys of the dog’s brain by himself and by his col- 
eague Scharff [(5). p. 179]. He gives no reference. 
