x THE FOEE-BEAIN G05 



It was found that in each of the three animals the cortical lesion 

 had not extended at all points to the limits assigned by Campbell 

 to the area striata, while at others it had exceeded them. A 

 small area in the front and deeper parts of the lower surface of 

 the area which lies on the tentorium escaped, while on its upper 

 and mesial surface the lesion extended somewhat further inwards 

 towards the parietal lobe. 



The failure to destroy the whole of the area striata is, however, 

 quite inadequate to explain the discrepancies in the results, 

 particularly if we remember that, according to Minkowski, there 

 is a projection of the retinal element on to the visual cortex ; the 

 anterior region of the area striata would correspond with the 

 upper segment of the retina, the posterior region with its lower 

 segment. Since the portion of the area striata remaining intact 

 corresponds only with about the twentieth part of the total area, 

 it is easy to see that if Minkowski's theory were correct there 

 must have been absolute and permanent blindness of nineteen- 

 twentieths of both retinae, which would readily have been detected 

 in our careful and repeated investigations. 



It has not therefore been demonstrated that the area striata 

 represents the whole of the visual sphere, or is more than its focal 

 area. This doubt is borne out by careful examination of the 

 microscopical preparations in our laboratory with the best technical 

 methods available. Till the contrary is proved, we are not justified 

 in assuming that there is not in dogs a definable area of the cortex 

 with a structure similar to that of the calcarine region of the 

 human brain. 



Further, it is indisputable that the whole of the visual 

 functions, including the visual reflexes, are not localised in the 

 cortex, and that part the most elementary of them are subserved 

 by sub-cortical centres. It is impossible to overlook the results 

 < ii' our earlier researches which demonstrated, in dogs as well as 

 in the macaque monkey, that the blindness incident on bilateral 

 extirpation of the occipital lobe is temporary; and that it 

 becomes reduced in a few days to an amblyopia which gradually 

 disappears till the symptoms are merely those of psychical 

 blindness, in which the animals see, but fail to recognise the 

 objects which they see. All this was confirmed by Lo Monaco ; 

 he found, after removing the two occipital lobes in bulk, that the 

 blindness was neither absolute nor permanent in his dogs, and 

 only became so after the subsequent operative destruction of the 

 optic thalami. 



Evidently Minkowski was led away by the preconceived ideas : 

 () that the visual sphere was confined to and strictly localised 

 in the area striata; (b) that all the visual functions had their 

 centre in the cerebral cortex. 



If these two propositions were generally applied to the different 



