THE CEREBRAL CORTEX. 

 By E. A. Schafer. 



Contents. — General Functions, p. 697 — Results of Removal of whole Cortex, 

 p. 698 — of one Hemisphere, p. 704 — Results of Artificial Excitation, p. 705 — 

 Character of Muscular Contractions resulting from Excitation, p. 707 — Other 

 Phenomena resulting from Excitation, p. 713— Effects on Respiration, p. 713 — 

 On Circulation, p. 714 — On the Pupil, p. 715— On the Secretions and on the 

 Muscular Tissue of the Viscera, p. 716 — Heat Centres, p. 717 — Epilepsy, p. 

 718 — Special Localisations — The Motor Areas and Centres, p. 722 — 

 Sensory (?) Functions of Motor Areas, p. 724 — Results of Stimulation and 

 Removal of Particular Areas, p. 732 — Associated Movements, p. 735 — The 

 Principal Parts of the Motor Cortex of the Monkey, p. 736 — The Head and 

 Eyes Area, 738 — Face Area, p. 740— Arm Area, p. 743— Leg Area, 744 — Trunk 

 Area, p. 745— The Motor Centres in the Orang, p. 745 — The Motor Centres in 

 Man, p. 747 — The Sensory Areas of the Cortex, p. 749 — The Visual Area, p. 752 

 — The Auditory Area, p. 761 — The Olfactory and Gustatory Areas, p. 763— The 

 Localisation of Tactile Sensibility, p. 766 — Latent Regions of the Cortex, 

 p. 769 — Hypothesis of Association Centres of Flechsig, p. 771 — Aphasia, p. 774 

 — Connections of Cortical Centres with one another and with Lower Centres, 

 p. 776. 



General Functions. 1 



The cerebral cortex is the seat of the intellectual functions, of 

 intelligent sensation or consciousness, of ideation, of volition, and of 

 memory. That this is so is proved by the observation in man of cases 

 of defective cerebral development and destructive disease. An 

 individual with defective cerebral development is idiotic, in proportion 

 to the amount of defect. It has not hitherto been shown that idiocy is 

 associated especially with defect of any one particular region or of one 

 hemisphere more than the other ; probably in all cases of marked idiocy 

 the defect is bilateral. Similarly, an individual with extensive destruc- 

 tion of the cortex cerebri, the result of accident or disease, becomes 

 mentally defective, the memory is lost, sensations are no longer rightly 

 appreciated, ideas are confused, and the volitional power is disordered, 

 diminished, or absent. These changes occur, not only as the result of 

 affections of the cortex, but also from lesion of the fibres which connect 

 the cortex with the " lower levels " of the central nervous system. 



The term " level " in connection with the central nervous system was 

 introduced by Hughlings Jackson to imply stages of complexity of the sensori- 



1 An admirable historical and critical account of the functions of the brain, including 

 many references to the views and researches of both older and more modern investigators, 

 is given by Professor J. Soury in the article "Cerveau," in Richet's "Diet, de physiol.," 

 Paris, 1897, fascs. 5 and 6. For a fuller discussion of many of the questions raised in the 

 recent rapid progress of research in this branch of physiology, than can well be introduced 

 here, the student may be referred to that article ; and the more so because the views 

 which are taken by Professor Soury are, on some questions, different from those which 

 are advocated here. See also " Le systeme nerveux," by the same author, Paris, 1899, 

 which is an extension of the above article. 



