THE MORPHOLOGICAL SUBDIVISION OF THE 



BRAIN. 



C. JUDSON HERRICK. 



{From the Anatomical Laboratory of the Unive'stty of Chicago.) 



The great diversity in the internal organization of different 

 parts of the nervous system makes demands on the morphologist 

 for a much more minute regional subdivision than is necessary 

 with most other organs; and at the same time this diversity, to- 

 gether w^ith the intricate interrelations between the various parts, 

 makes such an analysis the more difficult. 



The subdivision of the human brain, as made by the first anato- 

 mists on the basis of gross external form, has a certain functional 

 as well as morphological basis; but when the attempt was made to 

 study the regions so named comparatively, the morphological 

 imperfections of the scheme became at once apparent. Any fur- 

 ther attempt to utilize uncritically in morphology the "regions" as 

 customarily defined in the older human neurology is misdirected 

 energy. 



The clear recognition of this fact early led Professor His to 

 seek in his embryological studies a safer guide to cerebral mor- 

 phology, and the result of his labors as finally formulated is incor- 

 porated in the BNA nomenclature. 



But the cerebral analysis of Professor His is based almost 

 wholly on human embryology and therefore inevitably shares 

 some of the same defects as a scheme based on the human adult; 

 for the human embryonic brain at all stages is very far indeed from 

 giving a true picture of ancestral phylogenetic conditions. And 

 there can be no sound morphology which does not rest on a phylo- 

 genetic basis. And moreover the dynamic element in modern 

 morphology requires throughout a closer correlation between struc- 

 ture and function than any purely embryological or anatomical 

 scheme can effect. 



