author's abstract of this paper issued 

 by the bibliographic service october 27- 



COMPARATIVE STUDIES ON THE GROWTH OF THE 

 CEREBRAL CORTEX 



II. ON THE INCREASE IN THE THICKNESS OF THE CEREBRAL CORTEX 



DURING THE POSTNATAL GROWTH OF THE BRAIN. 



ALBINO RAT 



NAOKI SUGITA 



From The Wistar Institute of Anatomy and Biology 



fWELVl! FIGURES AND TWELVE CHARTS 



I. INTRODUCTION 



The object of this paper is to present the data collected upon 

 the increase in the thickness of the cerebral cortex of the albino 

 rat from birth to maturity and so to give an insight into the 

 postnatal growth of one important portion of the cerebrum. A 

 study of this kind may be of value in several ways: It should be 

 of fundamental biological interest, it should be useful for refer- 

 ence in experimental work on the central nervous system and in 

 connection with extensive data on the rat collected by Donald- 

 son ('15), and finally it should shed some hght on comparative 

 psychology. 



Papers on the thickness of the cerebral cortex of the mature 

 human brain have been published by several anatomists, for 

 example, Schwalbe ('81), Donaldson ('91), Hammarberg ('95), 

 Kaes ('05, '07), Brodmann ('09), etc. His ('04) has also carefully 

 described the developmental changes of the cerebral cortex in 

 the early fetal period of the human brain, including the cortical 

 thickness. Furthermore, there has been only one study on the 

 development of the human cortex after birth, a paper by Kaes 

 ('07) which, however, is unfortunately open to very serious criti- 

 cism. Brodmann ('09) has made an extensive collection of re- 

 sults obtained by comparative anatomists on the cerebral cortex 

 in several orders of the mammals. It is not possible, however, 



511 



