228 University of California Publications in Anatomy C^^ol. 2 



example Ferrier-Tiirner, Luciani, and S. I. Franz.) Thus in Franz's 

 eight monkeys the striate area was not in a single instance removed 

 completely, nor was the visual radiation interrupted entirely, usually 

 half or even considerably more of the striate area or of the visual 

 radiation remained intact (so far as one can judge from illustra- 

 tions in Franz' paper). The advantage of experimental anatomical 

 investigation (or, better, of a combined anatomical and physiological 

 procedure) unquestionably lies in the fact that it furnishes reliable 

 data as to the terminal regions of the afferent paths investigated, thus 

 indicating where to operate. By showing the location and the extent 

 of the "primary" or projectional cortical regions of the hemisphere 

 for the somato-sensory, auditory, and visual paths, anatomical investi- 

 gation affords a sound basis for further research on cortical functions 

 in primates and hence in man; in particular: (1) for investigating 

 the distinctive function of the "gateways" of the cerebral cortex by 

 the isolated removal or destruction of the projection areas or parts of 

 these, of the macular cortex, of the perimacular cortex, of special 

 areas of the precentral, and of the postcentral somatic sensory cortex, 

 of the auditory areas a and x together and separately, and so forth, 

 on one and on both sides; (2) for studying the nature and the sites 

 of higher integrative and other processes localized in the intercalated 

 regions by isolated removal of parts or of whole regions not directly 

 related to the afferent paths. In the future it must be kept in mind 

 that if complete destruction of the sensory cortex be desired, its "focal 

 or nuclear zone" must also be removed. Furthermore, when investi- 

 gating special receptor functions of the postcentral or of the precentral 

 areas, the ease with which the "focal zone" of the somatic sensory 

 cortex, as well as its portion of the thalamo-cortical radiation, can be 

 damaged, either from the postcentral or from the precentral convolu- 

 tion, must be taken into consideration. This being true, only the 

 results yielded by refined operative technique followed by a thorough 

 anatomical examination will be accepted as conclusive. What is true 

 for the somatic sensory cortex is valid also for the study of the audi- 

 tory and of the visual areas. To destroy the auditory projection area 

 the entire ventral wall of the Sylvian fossa as far inward as the inner 

 or vertical wall of that fossa must be removed. (The question, how- 

 ever, remains whether this alone will be enough, since, as stated pre- 

 viously, the function of the area x is unknown.) Similarly the visual 

 projection cortex cannot be considered as completely destroyed unless 

 the entire striate area has been removed including the portion buried 



