,AUTHOR’S ABSTRACT OF THIS PAPER ISSUED 
BY THE BIBLIOGRAPHIC SERVICE, MARCH 30 
COMPARATIVE STUDIES ON THE GROWTH OF THE 
CEREBRAL CORTEX 
VIII. GENERAL REVIEW OF DATA FOR THE THICKNESS OF THE 
CEREBRAL CORTEX AND THE SIZE OF THE CORTICAL CELLS IN 
SEVERAL MAMMALS, TOGETHER WITH SOME PGSTNATAL GROWTH 
CHANGES IN THESE STRUCTURES 
NAOKI SUGITA 
From The Wistar Institute of Anatomy and Biology 
THREE FIGURES AND TWO CHARTS 
‘I. INTRODUCTION 
Years ago Schwalbe (’81) pointed out as characteristic somatic 
expressions, which might be taken to indicate the grade of in- 
telligence of a species of animals, the following four measure- 
ments on the brain: 1) total weight of the brain; 2) total num- 
ber of nerve cells in the brain; 3) total area of the surface of the 
hemispheres of the brain, and 4) the thickness of the cerebral 
cortex. Since then he and many other neurologists have en- 
deavored to gather data on the morphological evidence for the 
development of mental ability. Donaldson and Hatai (‘The 
Rat,’ Donaldson, ’15) have made systematic observations on 
the growth changes in the central nervous system as well as in 
other organs and systems, using exclusively the albino rat. As 
a result of their investigations, the postnatal growth of the brain 
and the spinal cord, in gross measurements, and the relations of 
these to the other systems during growth have been deter- 
mined. In line with these studies, I also made further re- 
searches on the growth in the thickness of the cerebral cortex, 
the size and shape of the cortical nerve cells and the relative 
number of the cortical cells in both the Norway and albino rats. 
The results of these researches have been already presented 
(Sugita, 717, 717 a, 718, 718 a, ’18b, 718 c¢, ’18 d), with references 
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THE JOURNAL OF COMPARATIVE NEUROLOGY, VOL. 29, NO. 3 
