862 A MANUAL OF PHYSIOLOGY 



veritable lobe, called from its shape the pyriform lobe ; from its 

 supposed function, the rhinencephalon. The centre for taste is 

 supposed to be situated in the same region as the centre for smell 

 (in the hippocampal convolution posterior to the uncinate gyrus). 

 Ordinary and Tactile Sensations, including the muscular sense, 

 have been located in the Rolandic area (p. 856) ; and there are 

 good grounds for believing that afferent fibres from the joints, 

 the muscles and their accessory structures and the skin ter- 

 minate here in arborizations which come into contact either 

 with the motor pyramidal cells, or with intermediate cells which 

 link them to the pyramidal cells. 



Aphasia. Words are, at bottom, arbitrary signs by which certain 

 ideas are expressed. The power of intelligent communication by 

 spoken or written language may be lost : (i) by paralysis of the 

 muscles of articulation or the muscles which guide the pen ; (2) by 

 inability to hear or see the spoken or written word i.e., by deafness 

 or blindness ; (3) by inability to comprehend the meaning of spoken 

 or written language, although sensations of hearing and sight may 

 not be abolished -that is to say, by inability to interpret the auditory 

 or visual symbols by which ideas are conveyed ; (4) by inability to 

 clothe ideas in words, although the words may be present in the 

 patient's consciousness, and the ideas conveyed by speech or writing 

 may be comprehended. Neither (i) nor (2) is considered to consti- 

 tute the condition of aphasia ; (3) represents what is called amnesia, 

 or sensory aphasia ; (4) is aphasia in the ordinary restricted sense, or 

 motor aphasia. 



Motor aphasia may be divided into two varieties subcortical 

 or pure motor aphasia, and cortical, or Broca's aphasia. In 

 the subcortical type the patient understands speech and writing 

 perfectly, and is able to write normally ; but he cannot speak spon- 

 taneously or read aloud, or repeat words when requested to do so. 

 He may know quite well what to reply in answer to a question, but 

 the words necessary to express his meaning do not come to him. 

 In Broca's type of aphasia, which is the most common form, the 

 patient may understand spoken and written words often imper- 

 fectly, it is true but he is unable to speak spontaneously, to repeat 

 words spoken to him, and to read aloud. Unlike the subcortical 

 type of motor aphasic, he has difficulty in reading by the eye with- 

 out articulation, and in writing spontaneously or to dictation. 

 There is often or always a certain amount of intellectual deficiency. 

 The gradations in the loss of the expressive factor in speech may be 

 infinite. A patient may sometimes sing a song without a single 

 slip in words or measure, and yet be unable to speak or write it. In 

 a case recorded by Larionow an aphasic could speak only one 

 syllable, ' tan,' but could sing the ' Marseillaise.' In certain cases 

 the change is confined to loss of the power of spontaneous speech, 

 and the patient may be able to read intelligently. Sometimes he 

 can express his ideas in speech, but not in writing (agraphia) . Some- 

 times the loss is restricted to certain sets of ideas. For example, a 

 boy was injured by falling on his head. Typical symptoms of motor 

 aphasia developed, but the power of dealing with ideas of number 

 was n6t interfered with, and the boy continued to learn arithmetic 

 as if nothing had happened. Proper names and nouns are more 



