FUNCTIONS OF THE BRAIN. 51 



giglit altogether.* Recent pathological annals seem to offer 

 a few such cases. f Meanwhile there are a number of cases 

 of mental blindness, especially for written language, coupled 

 with hemianopsia, usually of the rightward field of view. 

 These are all explicable by the breaking down, through 

 disease, of the connecting tracts between the occipital lobes 

 and other j)arts of the brain, especially those which go to 

 the centres for speech in the frontal and temporal regions of 

 the left hemisphere. They are to be classed among distur- 

 bances of conduction or of association ; and nowhere can I find 

 any fact which should force us to believe that optical images 

 need| be lost in mental blindness, or that the cerebral 

 centres for such images are locally distinct from those for 

 direct sensations from the eyes. § 



Where an object fails to be recognized by sight, it often 

 happens that the patient will recognize and name it as soon 

 as he touches it with his hand. This shows in an interest- 



* Nothnagel {loc. cit. p. 22) says : " Dies trifft iiber nicJit zu." He gives, 

 however, no case in support of his opinion that double-sided cortical lesion 

 may make one stone-blind and yet not destroy one's visual images ; so that 

 I do not knovF whether it is an observation of fact or an a priori as- 

 sumption. 



f In a case published by C. S. Freund: Archivf. Psychiatric, vol. xx, the 

 occipital lobes were injured, but their cortex was not destroyed, on both 

 sides. There was still vision. Cf. pp. 291-5. 



X I say ' need. ' for I do not of course deny the possible coexistence of the 

 two symptoms. Many a brain-lesion might block optical associations and at 

 the same time impair optical iiiiagiuatiou, without entirely stopping vision. 

 Such a case seems to have been the remarkable one from Charcot which I 

 shall give rather fully in the chapter on Imagination. 



§ Freund (in the article cited above ' Ueber optische Aphasie und 

 Seeleublindheit ') and Bruns (' Eiu Fall von Alexie,' etc., in the Neuro- 

 logisches Centralblatt for 1888, pp. 581, 509) explain their cases by broken- 

 down conduction. Wilbrand, whose painstaking monograph on mental 

 blindness was referred to a moment ago, gives none but a jww"/ reasons for 

 his belief that the optical 'Erinnerungsfeld ' must be locally distinct from 

 the Wahrnehmungsfeld (cf. pp. 84, 98). The a priori reasons are really the 

 other way. Mauthner (' Gehirn u. Auge ' (1881), p. 487 flf.) tries to show 

 that the 'mental blindness' of Mimk's dogsand apes after occipital mutila- 

 tion was not such, but real dimness of sight. The best case of mental 

 blindness yet reported is that by Lissauer, as above. The reader will also 

 do well to read Bernard : De TAphasie (1885) chap v: Ballet : Le Langage 

 In terieur (1886), chap vm ; and Jas Ross's little book on Aphasia (1887), 

 p. 74. 



