706 FUNCTIONS OF THE CEREBRO -SPINAL NERVOUS SYSTEM. 



to execute all the movements required for articulation and phonation, though, 

 from the breach in the mechanism for translating ideas into words, he is 

 speechless. This is pure Aphasia, but cases uncomplicated by further dam- 

 age are rare, while speechlessness of a totally different character is often 

 confounded with Aphasia. The nervous mechanism may, in fact, be injured 

 at different points. Below the third frontal convolution, lesion in the Corpus 

 Striatum may cause impairment of articulation, or in the medulla or its 

 nerves more or less complete loss both of phonation and articulation (alalia). 

 Here the speechlessness is simply from motor paralysis, but other forms of 

 speechlessness arise from lesions in the cerebral or mental mechanism. Cases 

 have been met with in which a man could speak and write correctly while 

 unable to read a single word even of what he had himself written, or to 

 name the most familiar object shown to him ; the association by which the 

 visual perception called up the name was broken. Let the association be- 

 tween the auditory perception and the name be similarly broken, and we 

 have the explanation of the perplexing cases 1 in which a patient has lost all 

 comprehension of articulate sounds, and neither understands what is said to 

 him nor what he says, while he responds promptly to signs, and appears to 

 be intelligent. These are forms of Amnesia or loss of memory for words, 

 but there are other more common forms of Amnesia in which a patient un- 

 derstands spoken words, but cannot recall them mentally so as to rehearse a 

 phrase or proposition in his mind. Very frequently a degree of Amnesia is 

 associated with Aphasia, the various degrees and combinations of loss of 

 memory for words and loss of memory how to say words depending upon 

 the region and extent of cortex involved, or upon the severance of fibres 

 connecting together different sets of convolutions. Again, in extensive dis- 

 ease of the Cortex there is no speech because there is no idea ; this is 

 dementia or mutism. 



570. The general result of pathological investigation is, that the Cerebrum is 

 the instrument of all those psychical operations, which we include under the 

 general term Intellectual, whilst it also affords, in part at least, the instrumental 

 conditions of Emotional states; and that all those muscular movements which 

 result from voluntary determinations, or which are directly consequent upon 

 emotional excitement, have their origin in its vesicular substance, though the 

 motor impulse is immediately furnished by the Cranio-Spinal apparatus, upon 

 which the Cerebrum plays ( 547 ). It does not hence follow, however, that 

 the Cerebrum has such a direct relation to the Mind, that the consciousness 

 is immediately and necessarily affected by changes taking place in its own 

 substance; and, however startling the proposition may at first sight appear, 

 that the organ of the intellectual operations is not itself endowed with con- 

 sciousness, a careful consideration of the relations of the Cerebrum to the 

 Sensory Ganglia will tend to show that there is no a priori absurdity in such 

 a notion. For if the connection of the vesicular matter of the Cerebral Hemi- 

 spheres with the Sensorial Centres, be anatomically the same as that which 

 exists between these centres and the Retina or any other peripheral expan- 

 sion of vesicular matter in an organ of sense, which we have seen that it is 

 (^ ; "><>4), and if the same kind of change may be excited in the Sensorial 

 Centres by an impression from each source, which has been shown to be a 

 matter of common occurrence ( 546), it can scarcely be deemed unlikely 

 that the Seusorial Centres should be the seat of consciousness, not merely 

 for the impressions transmitted to them by the nerves of the external senses, 

 but also for the impressions brought to them by the "nerves of the internal 



1 See Hroadbent, Med.-Chir. Trans., 1872-5, to whom the Editor is indebted for 

 much aid in drawing up this section, and for the Figure by which it is illustrated. 



