262 NAOKI SUGITA 
changes, briefly stated, are as follows: The average thickness of 
the cortex diminishes rapidly from his first entry (three months 
old, 5.58 mm.) to the twenty-third year (4.44 mm.) and is fol- 
lowed by an increase up to the forty-fifth year (5.71 mm.), where 
it is to be noted that the thickness attained is even greater 
than that at birth. Then it undergoes a second thinning up 
to the-old age (at ninety-seventh year, his last entry, 4.62 mm.). 
These conclusions have been disputed by Donaldson (’08) 
and by Brodmann (’09), and I am in agreement with these critics | 
that Kaes’ results cannot be taken seriously. 
Brodmann (’08), in his paper on the cortical measurement, 
has noted only in a general way the average cortical thickness 
at the lateral surface of the hemisphere at several ages, as shown 
in table 10 (columns A and C). Nevertheless, these data can 
be used for a comparison. 
Donaldson (’08) has compared the albino rat with man in 
respect to the growth of the brain and reached the conclusion 
that man and the rat show growth curves for the brain which 
are similar in form when the data are compared at equivalent 
ages, and the condition of the brain of the rat at five days of 
age is taken as like that of the human brain at birth. The rela- 
tive growth rates of the rat and man are as 30 to 1 and the brain 
of the child at one year corresponds to that of the albino rat at 
seventeen days of age in its stage of development (Donaldson, 
MS.). These statements are also confirmed by me for the cor- 
tical thickness, as shown in table 10 (see below), and I have 
already noted that the transitional cortical cell layers, which 
are no longer to be seen in a new-born child, do not disappear 
in the albino rat until after four days of age (Sugita, 717 a, p. 539). 
From these relations, we conclude that the course of growth in 
the thickness of the cerebral cortex in man and the albino rat 
would probably be similar, if the brains were compared at the 
equivalent ages. Such a comparison is attempted in table 10. 
Here the increase in cortical thickness in man and in the albino 
rat is compared, employing data given by Brodmann (’08) and 
by me (Sugita, ’717a). From the age (column A) given by 
Brodmann, the approximate brain weight (column B) was de- 
