FUNCTIONS OF THE BRAIN. 45 



sphare ' definitely, and says that blindness must result 

 when the entire shaded part, marked A, A, in Figs. 12 

 and 13, is involved in the lesion. Discrepant reports } 

 of other observations he explains as due to incomplete 



Fig. 12. Fig. 13. 



The Dog's visual centre according to Munk, the entire striated region, A, A, being the 

 exclusive seat of vision, and tlie dark central circle, A', being correlated with the 

 retinal centre of the opposite eye. 



ablation. Luciani, Goltz, and Lannegrace, however, con- 

 tend that they have made complete bilateral extirpations 

 of Munk's Sehsphiire more than once, and found a sort 

 of crude indiscriminating sight of objects to return in a 

 few weeks.* The question whether a dog is blind or not 

 is harder to solve than would at first appear ; for simply 

 blinded dogs, in places to which they are accustomed, show 

 little of their loss and avoid all obstacles ; whilst dogs 

 whose occipital lobes are gone may run against things fre- 

 quently and yet see notwithstanding. The best proof that 

 they may see is that which Goltz's dogs furnished : they 

 carefully avoided, as it seemed, strips of sunshine or paper 

 on the floor, as if they were solid obstacles. This no really 

 blind dog would do. Luciani tested his dogs when hungry 

 (a condition which sharpens their attention) by strewing 



* Luciani und Seppili : Die Functions-Localization auf der Grosshiru- 

 rinde (Deutsch von Fraenkel), Leipzig, 1886, Dogs M, N, and S. Goltz in 

 Pflliger's Arcbiv, vol. 34, pp. 490-6; vol. 43, p. 454. Cf. also Munk: Berlin 

 Akad. Stzgsb. 1886, vii, viii, pp. 113-121, and Loeb: Pfluger's Archiv, 

 vol. 39. p. 337. 



