GROWTH OF THE CEREBRAL CORTEX 263 
TABLE 10 
Giving a comparison in the course of increase in cortical thickness in man and in 
the albino rat, according to data given by Brodmann (’08) and by Sugita (17 a). 
Approximate brain weight in man and in the Albino for the equivalent ages were 
assumed in round numbers according, respectively, to Vierordt (’90) and Don- 
aldson (08) 
A B (©: D E F G 
MAN ALBINO RAT 
| ; | Correspond- 
Approximate ing cortical 
Observed brain Thickness | thickness in 
Approximate} thickness of |weight,atthe) Equivalent [of the cortex}human brain, 
Age brain the cortex, | equivalent (observed) at ages when the 
weight Brodmann | (observed) age given in adult values 
(08) ages | Column E | inthe both 
(Donaldson) are taken as 
the standards 
grams mm. grams days mm. mm, 
Fetus 
8-9 months 1.0-1.5 Birth 0.80 1.25 
Birth 380 1.5-2.0 0.50 5 1.10 20s 
1 year 950 2 .0-3.0 1.10 Ue Lets 256 
Adult 1400 2.0-—4.0 1.90 Adult 1.90 3.00 
termined according to Vierordt (’90) and then the final weight 
(1400 grams) was entered corresponding to the adult brain weight 
of the albino rat (1.9 grams). The other corresponding brain 
weights of the Albino of the equivalent ages were entered also 
according to Donaldson (’08) (column D). The cortical thick- 
ness (column F) for the given brain weights of the Albino were 
then entered according to my former determination (Sugita, 
17 a). If the cortical thickness of the adult man be assumed 
as 3.00 mm. (the mean value of 2.0 to 4.0 mm.) and the corre- 
sponding thickness at each age be calculated on the basis of the 
course of increase in cortical thickness in the Albino (given 
in column F), the results given in column G—a mere inference, 
to be sure—are fairly in accord with the figures presented by 
Brodmann (column C). 
In this connection, I had the opportunity, through the courtesy 
of Dr. W. H. F. Addison, to prepare sections and examine the 
cortical thickness at the dorsal part of the gyrus centralis ante- 
rior (regio Rolandica) from a child thirteen months old (ma- 
terial hardened in 4 per cent formaldehyde, imbedded in paraf- 
