FUNCTIONS OF THE BRAIN. 47 



Brown and Schaefer, found no disturbance of sight from 

 destroying the angular gyri alone, although Terrier found 

 blindness to ensue. This blindness was probably due to 

 inhibitions exerted in distans, or to cutting of the white 

 optical fibres passing under the angular gyri on their way 

 to the occipital lobes. Brown and Schaefer got complete 

 and j)ermanent blindness in one monkey from total destruc- 

 tion of both occipital lobes. Luciani and Seppili, perform- 

 ing this operation on two monkeys, found that the animals 

 were only mentally, not sensorially, blind. After some 

 weeks they saw their food, but could not distinguish by 

 sight between figs and jjieces of cork. Luciani and SejDpili 

 seem, however, not to have extirpated the entire lobes. 

 When one lobe only is injured the affection of sight is 

 hemiopic in monkeys : in this all observers agree. On 

 the whole, then, Munk's original location of vision in the 

 occipital lobes is confirmed by the later evidence.* 



In man we have more exact results, since we are not 

 driven to interjjret the vision from the outward conduct. 

 On the other hand, however, we cannot viidsect, but must 

 wait for pathological lesions to turn up. The pathologists 

 who have discussed these (the literature is tedious ad libi- 

 tum) conclude that the occipital lobes are the indispensable 

 part for vision in man. Hemiopic disturbance in both eyes 

 comes from lesion of either one of them, and total blindness, 

 sensorial as well as psychic, from destruction of both. 



Hemiopia may also result from lesion in other parts, 

 esjDecially the neighboring angular and supra-marginal gyri, 

 and it may accompany extensive injury in the motor region 

 of the cortex. In these cases it seems probable that it is 

 due to an actio in distans, probably to the interruption of 



* H. Munk : Functionen der Grosshirnrinde (Berlin, 1881), pp. 36-40. 

 Ferrier : Functions, etc., 2ded., chap, ix, pt. i. Brown and Schaefer: 

 Philos. Transactions, vol. 179, p. 331. Luciani u. Seppili, op. cit. pp. 

 131-138. Lannegrace found traces of sight with both occipital lobes de- 

 stroyed, and in one monkey even when angular gyri and occipital lobes 

 were destroyed altogether. His paper is in the Archives de Medecine 

 Experimentale for January and March, 1889. I only know it from the 

 abstract in the Neurologisches Centralblatt, 1889, pp. 108-420. The reporter 

 doubts the evidence of vision in the monkey. It appears to have consisted 

 in avoiding obstacles and in emotional disturbance in the presence of men. 



