1058 VOLUNTARY MOVEMENTS. [BOOK in. 



deduction that the cortical speech area does not carry out the 

 whole of the coordination of the impulses involved in articulation. 

 That coordination is exceedingly complex, and we ought perhaps 

 to recognize in it more than one degree or kind of coordination. 

 The failure of articulation in disease of the bulb shews that a 

 certain amount of coordination takes place there ; for the affec- 

 tions of speech due to bulbar disease are not the same as those 

 resulting from the mere loss of this or that muscle or nerve. We 

 must of course admit that some, possibly a great deal, of coordi- 

 nation of a certain kind takes place in the cortex, for the bulb 

 cannot by itself be made to speak ; exactly how much, the 

 knowledge at present at our disposal leaves a matter of great 

 uncertainty; but it is sufficient for our present purpose to 

 recognize that whatever may be the nature of the events taking 

 place in the cortical area during the act of speech, those events 

 make use of the machinery already provided in the bulb. The 

 word spoken does not start, so to speak, ready made in the cortex ; 

 it is not that a group of impulses start from the cortex with their 

 coordination fully achieved, and pass along certain nerve fibres to 

 certain muscles, making their way without change through the 

 tangle of the bulb, as if this were merely a bundle of lines 

 offering paths for, but exercising no influence over the impulses. 

 We must rather suppose that something takes place in the cortex 

 of the third frontal convolution, as the result of which efferent 

 impulses pass along the appropriate fibres of the pyramidal tract 

 to the bulb, and there start a series of events leading to the issue 

 of the coordinated impulses by which the word is spoken. 



661. We have no reason whatever to think that the cortical 

 area for speech differs in its fundamental characters from other 

 divisions of the motor region, and are justified in carrying on to 

 other areas the deduction we have just drawn in connection with 

 the speech area. With that end in view we may now turn back 

 to the experimental results obtained on the dog, and it will make 

 our discussion simpler if we take as an illustration some large area 

 such as the forelimb area. 



We have seen that stimulation of this area produces what we 

 may, to start with, speak of simply as movements of the fore-limb; and 

 guided by the analogy of speech in man we may confidently conclude 

 that when the dog voluntarily moves the fore-limb, the act is earned 

 out by means of events taking place in the fore-limb cortical area. 

 The simplicity of the electrical phenomena resulting from cortical 

 stimulation, which we described in 657, might at first sight lead 

 us to conclude that the whole matter was fairly simple ; and indeed 

 some writers appear to entertain the conception that in a voluntary 

 movement such as that of the fore-limb, all that takes place is that 

 the ' will' stimulates certain cells in the cortical area causing the 

 discharge of motor impulses along the pyramidal fibres connected 

 with those cells, and that these motor impulses travel straight down 



