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PHYSIOLOGY 



that there is no loss of intelligence in these cases of so-called motor aphasia 

 does not bear investigation. Although as patients they may comport 

 themselves reasonably, as soon as they have to perform any duties which 

 have been learnt by them in connexion with their ordinary avocations 

 they show their deficiency. They are incapable of transacting ordinary busi- 

 Amentia Dementia 



I i :. 235. Types of lesions giving rise to deficient intellectual power. In amentia, 

 the deficiency is due to failure of development ; in dementia, to atrophy of 

 the cells (especially small pyramidal) previously present in the cortex. (MoTT-) 



ness, at any rate to the extent to which they were before the lesion. The 

 amount of impairment of intelligence will vary in different cases according 

 to the extent of the lesion. Thus softening affecting the occipital lobe 

 may, with hemianopia, cause ' word-blindness ' or alexia, a loss of power 

 of appreciating the meaning of written words. In most individuals, and 

 certainly in the uneducated, this power may be cut out altogether without 

 interfering considerably with the mental powers. On the other hand, 

 from babyhood upwards we have learnt the meaning of words and their 



