GROWTH OF THE CEREBRAL CORTEX 261 
stant und bilden ein Hauptmerkmal der struktuellen Ver- 
schiedenheiten der Gehirnoberfliche; jedes Strukturfeld besitzt 
demnach eine bestimmte, mittlere Durchschnittsbreite, durch 
welche es sich von den Nachbarfeldern auszeichnet.’? Onthe 
other hand, local variations within a fixed area are small, while 
individual differences between different brains for each locality 
may run sometimes as high as 0.5 mm. or more. 
VI. INCREASE IN CORTICAL THICKNESS DURING THE GROWTH OF 
THE BRAIN OF THE MAN 
From the point of view of the growth changes, there have been 
only few studies on the human cerebral cortex ever published.’ 
Kaes (’05, ’07, 09), employing forty-one human brains (twenty- 
eight males and thirteen females, normal and pathological com- 
bined) of different ages and of different grades of intelligence, 
studied the cerebral cortex for the purpose of following the 
growth changes in it. He took his sections from twelve locaii- 
ties in each hemisphere, stained the fibers by Weigert’s method 
and measured the so-called cortical thickness from the ectal 
border of the Meynert’s arcuate fibers (or fibrae propriae) to the 
ectal border of the zonal layer. His conclusions on the growth 
2 His (’04) has given the following values as the cortical thicknesses meas- 
ured at different localities of the hemisphere of the human embryos in early 
months, at different stages of intrauterine development—measured directly on 
the sections imbedded in paraffine. 
| 
sonor | arconrus | AT LATERAL| “Slt'on | “warn or | ALMEDIAN |“ “opt” 
SMBENOS | SESIANOM | THALAMUS | (Basar pant) | Gmrp Pann) | MEMISPHERE | cory 
mm Ke B B H Be 
weeks 
1 50-55 
2 65-75 
4 150 130 110 60 
5 360 160 120 50 
6 800 300 130 90 40 
7 1300 600 300 170 110 30 
8 2000 900 400 200 130 30 
