178 University of California Publications in Anatomy [Vol.2 



methods but in a decrease of the acuity of the "central" vision (as 

 for example in disseminate sclerosis; compare Herrman, 1929). 



In the occipital operculum of the monkey's brain there can regu- 

 larly be observed a shallow sulcus or impression running somewhat 

 obliquely horizontal across the occipital lob« from the oecipital pole 

 toward the sulcus simialis {Ss), terminating not far from the latter in 

 a shallow notch and dividing the operculum into an upper and a lower 

 half {80s in fig. 21, sulcus occipitalis superior of G. Elliot Smith, sul- 

 cus calcarinus externus of Cunningham-Smith, in anthropoids and in 

 man). This sulcus might well correspond, in my opinion, to the 

 horizontal meridian dividing the upper quadrants of both homonymous 

 hemimaculae from the lower quadrants. Its cortex receives particu- 

 larly dense bundles of the fine afferent visual fibers. It would seem, 

 then, that this shallow impression corresponds to the spot of the most 

 discriminative and the most analytic vision, that is, to the fovea cen- 

 tralis of the retina. This sulcus, especially its anterior notch, would in 

 fact be a fovea (recte hemifova) centralis corticalis. 



Objections have been made in recent times to the conception of a 

 fixed anatomical point to point projection of the retina upon the visual 

 cortex, especially of the macula (Goldstein, Fuchs). It has been 

 claimed that in cases of a central destruction of the macular cortex the 

 formation of a new "functional macula" was observed. The position 

 of this functional macula, accordingly, would correspond with an 

 eccentric spot of the hitherto extramacular portion of the hemiretinae. 

 But from the anatomical point of view it is inconceivable how the 

 highest organized and most perfectly differentiated structures of the 

 visual system, as undoubtedly the macular portion is (compare Cajal), 

 could in the adult and in a short time be substituted in such a perfect 

 way by the obviously less perfectly organized extramacular retina and 

 the corresponding portion of the visual system. It can be granted 

 that such a new "functional macula" could perhaps become the 

 "central spot of the still functioning portion of the retina" and of 

 the rest of the visual fields ; yet the function of such a ' ' pseudomacula ' ' 

 would necessarily remain less perfect than that of the normal macula. 

 To explain certain clinical symptoms observed in many, though not 

 in all cases of the hemianopsia of central origin, some investigators 

 thought it convenient to recur to the hypothesis of a dovible or a 

 bilateral representation of the macula (Heine, Jendrassik, Lenz, Wil- 

 brand, Henschen, R. A. Pfeifer, Niessl von Mayendorf, Foerster, 



