604 PHYSIOLOGY CHAP. 



not localised, however, to the calcarine region, but diffuse all over 

 the controlateral occipital lobe. 



Minkowski (1911) continued the work of Tschermak and 

 Kurzveil. Starting from the localisation and extent of the striate 

 area, as described by Campbell on the upper, middle, and inner 

 surfaces of the occipital lobe of the dog's brain (Fig. 301), he 

 attempted to show that the destruction of this area on one side 

 produces amaurosis or permanent blindness in the temporal three- 

 fourths of the visual field of the opposite side, while there is 

 transitory amaurosis in a small nasal portion of the homolateral 

 visual field. From this he concludes that the visual sphere 

 coincides perfectly in the dog with the area striata, and that the 

 greater part (over three-fourths) of each retina is represented in 

 the area striata of the occipital lobe of the opposite side, and the 

 small remaining part in the area striata of both sides, mainly, 

 however, on the homonymous. 



Bilateral removal of the striate area, according to Minkowski, 

 produces total and permanent blindness. He states that dogs 

 thus operated on for ever lose not merely perceptions but also 

 simple ocular reflexes to luminous stimulation, with the exception 

 of the pupil reflex. 



The sub-cortical optic centres alone cannot therefore, according 

 to this author, subserve even the simplest visual reflexes. 



We may ignore Minkowski's other statements and confine, 

 ourselves to the consideration of this conclusion, which he has 

 confidently described in much detail. It is so diametrically 

 opposed to our own results that we immediately instituted an 

 experimental control by three different students in our laboratory. 

 Up to the present the results of excising Campbell's striate areas 

 on both sides, in three young dogs, have been in contradiction with 

 the statement which Minkowski uses as the basis of his entire 

 theory of the visual sphere in dogs. 



During the first days after the operation, the three dogs which 

 had been deprived of Campbell's striate area on both sides were 

 not merely not blind, but were not even amblyopic. They were 

 capable, in walking, of avoiding contact or collision with the walls 

 surrounding them, the legs of chairs, or other furniture in the 

 vicinity. They never stumbled against obstacles placed on the 

 floor of the room, both irregularly and sometimes in lines and 

 close to each other, so that the dogs might easily have knocked 

 them over in passing between them, if their vision had been ever 

 so slightly affected. It was amazing to see how often they got by 

 without stumbling against any of the obstacles. 



Such a flagrant contradiction between Minkowski's statement 

 and our own observations was quite unexpected. To test it we 

 killed the three dogs in order to make sure by examination that 

 the whole of the area striata had been destroyed on both sides. 



