V] Fibre Arrii<i(i>i<itt in Vlsito-I'si/cli!*- Cortc.r 



To moot this hypothesis Cunningham's view that the human posterior calcarine fissure 

 has no equivalent in the anthropoid brain, of course, must be discarded'. 



OCCIPITAL OR VLSUO-PSYCHIO TYPE OF CORTEX. 



I am attaching the designation "occipital" or "visuo-psychic" to a readily-defined field 

 of cortex which immediately adjoins and almost surrounds the calcarine or visuo-sensory area. 

 The term visuo-psychic is of course not of new coinage ; it has been employed by many 

 writers in contradistinction to the term visuo-sensory. The employment of such distinguishing 

 terms is rendered necessary because the pathological, the experimental, and the anatomical 

 and embryological researches which have been undertaken to determine the precise regions 

 of the cortex in which visual sensations are centred and elaborated, afford grounds for believing 

 that cortical visual representation is of twofold character; that it consists of a primary station 

 in each hemisphere for the direct reception of impressions derived from homonymous halves 

 of both retinal fields a centre known by the name visuo-sensory and definitely proved to 

 exist and a secondary centre which probably serves for the further treatment of the rough 

 impressions, a centre which is probably of psychic nature and hence has been called visuo- 

 psychic. Although this centre, unlike the visuo-sensory, is doubtfully existent and doubtfully 

 located, yet the distinctive histological structure of the field of cortex, which I am about 

 to describe, strongly suggests that it possesses a special physiological function. Further, its 

 close relation to the visuo-sensory or calcarine area, and other points to which I shall have 

 occasion to refer, suggest in equal measure that it is the cortical centre for psychic visual 

 representation ; accordingly it seems justifiable in the meantime to apply to it the designation 

 visuo-psychic. 



1 Since writing the above my attention has been directed to some papers on the " Occipital Kegion " by Elliot 

 Smith, and as this writer's more important conclusions are drawn from facts of histology I embrace the opportunity 

 of referring to his work. The main point at issue is the question of the possibility of identifying the " Affenspalte " 

 in the Human Brain. Elliot Smith maintains that a study of the distribution of the cortex bearing a line of Gennali 

 affords an infallible solution of this notoriously controversial problem. He states that in a considerable proportion 

 of African and in some European human brains there exists on the lateral surface of the occipital lobe an indenture 

 which he calls the "sulcus luuatus,'' aud he holds that as the "calcarine" area or area striata bears the same 

 relation to this indenture stopping abruptly on its free edge as the same area does to the " Affenspalte " in the ape, 

 therefore the two fissures are homologous. 



At first I was inclined to doubt whether the facts of histology eonld be reconciled with this view, but a further 

 examination of the brains and casts in my collection and a reconsideration of the facts set forth in this research 

 convinces me that Elliot Smith's contention, or, I should say, the histological basis on which it rests, is perfectly 

 stable. If I read his work correctly a typical " sulcus luuatus " is to be located by its relation to the fissura 

 extrema of Seitz, it will run parallel with that fissure and be the next indenture in the lateral direction ; moreover, 

 the line of Gennari will be seen to creep out of the fissura extrema and end on the free surface a few millimetres 

 before the lunate indenture is reached. In short, using Bolton's anatomical terminology and, by the way, it is 

 surprising that Elliot Smith has overlooked this author's work the "sulcus lunatus" will become an external polar 

 sulcus, and in conjunction with Boltou's superior and inferior polar sulci will complete a lateral polar arc. Now on taking 

 observations with these guides I thiuk I have identified the sulcus luuatus in a considerable number of my specimens, 

 and what is more to the point I am prepared to endorse all that Elliot Smith writes on the similarity of relationship 

 of the area striata to this fissure and to the "Affenspalte," in man and the manlike ape, respectively. But here I must 

 quit this subject, leaving it to others to comment on the instability of the sulcus lunatus and other points bearing on 

 the homology under consideration. From the staudpoint of functional localisation there is no question that the fissure 

 to which the area striata stands fundamentally related is not the " Affenspalte " or its human equivalent, but the 

 calcarine, therefore nothing which I have previously written calls for alteration. It is still correct to say that in the 

 human brain, save the superior and inferior sulci of Bolton, there is no constant fissural boundary to the "calcarine" 

 area on the lateral surface of the hemisphere. 



