THE STUDY OF AN ATYPICAL CEREBRAL CORTEX 



D. DAVIDSON BLACK 



The Anatomical Department, Western Reserve University Medical School 



NINE FIGURES 



CONTENTS 



Introduction 351 



Description of cortical areas 354 



Discussion 360 



Cortical lamination 360 



Relation of cortex to afferent fibers 362 



Projection fibers entering mainly via zonal layer 363 



Projection fibers entering mainly via medullary center 364 



Regions destitute of thalamic fibers 365 



Trophic activities of afferent fibers 366 



Results of absence of trophic action 367 



Summary 368 



Literature cited 369 



INTRODUCTION 



In a previous paper (2) I have described briefly some of the 

 histological findings in a quite atypical cerebral cortex from a 

 cyclopian term foetus. In the present communication it is my in- 

 tention to deal with the structure of various areas in the same cor- 

 tex somewhat more fully, for it seems to me that these details are 

 warranted in view of the manner in which the cortical develop- 

 ment in this case illustrates several rather fundamental theories 

 concerning the growth of nervous tissue. 



The cerebrum in this case was represented by a single unpaired 

 vesicle, having an extensive expanded ependymal roof which was 

 attached to the recurved margin of a cup-shaped thickened base 

 representing the cortex proper. The attachment of the cerebral 

 vesicle to the thalamus was very slight and wholly basal. On 



351 



THE JOURNAL OF COMPARATIVE NEUROLOGT, VOL. 23. NO. 5 

 OCTOBER, 1913 



