FUNCTIONS OF THE SENSORY GANGLIA. 727 



place, in most exact accordance one with another; and the predetermined tone 

 is the result. This anticipated or conceived sensation is the guide to the mus- 

 cular movements, when as yet the utterance of the voice has not taken place ; 

 but whilst we are in the act of speaking or singing, the contractile actions are 

 regulated by the present sensations derived from the sounds as they are produced. 

 It can scarcely but be admitted, then, that the Will does not directly govern 

 the movements of the Larynx; but that these movements are immediately 

 dependent upon some other agency. 



757. Now what is true of the two preceding classes of actions is equally true 

 of all the rest of the so-called voluntary movements; for in all of them the 

 power of the Will is really limited to the determination of the result; and the 

 production of that result is entirely dependent upon the concurrence of a "guid- 

 ing sensation/' which is usually furnished by the very muscles that are called 

 into action. It is obvious, therefore, that we have to seek for some intermediate 

 agency, which executes the actions determined by the Will ; and when the facts 

 and probabilities already stated are duly considered, they tend strongly in favor 

 of the idea that even Voluntary movements are executed by the instrumental- 

 ity of the Automatic apparatus, and that they differ only from the automatic or 

 instinctive in the nature of the stimulus by which they are excited the deter- 

 mination of the Will here replacing, as the exciting cause of its action, the 

 sensory impression which operates as such in the case of an instinctive move- 

 ment, and which is still requisite for its guidance. 



758. This view of the case derives a remarkable confirmation from the ana 

 lysis of two classes of phenomena ; the first consisting of cases in which move- 

 ments that are ordinarily automatic are performed by voluntary determination, 

 or simply in respondence to an idea; the second consisting of those in which 

 movements originally voluntary come by habit to be automatically performed. 

 Of the first class, the act of Coughing is a good example. This action, which 

 is ordinarily automatic, may also be excited by a voluntary determination ; such 

 a determination, however, is directed to the result, rather than exercised in 

 singling out the different movements and then combining them in the necessary 

 sequence; and it thus seems obviously to take the place of the laryngeal or 

 tracheal irritation, as the primum mobile of the series, which, in its actual per- 

 formance, is as automatic in the latter case as in the former. So, again, we 

 know that many of the automatic movements which have been already referred to 

 as examples of the sensori-motor group ( 748), and which the Will cannot call 

 forth, may be performed in respondence to ideas or conceptions, which are Cere- 

 bral states that seem to recal the same condition of the Sensorium as that which 

 was originally excited by the Sensory impression. Thus it is well known that 

 the act of Vomiting may be induced by the remembrance of some loathsome ob- 

 ject or nauseous taste, which may have been excited by some act of "suggestion ;" 

 and the author has known an instance in which a violent fit of sea-sickness was 

 brought on by the sight of a vessel tossed about at sea, which recalled the former 

 experience of that state. So, the Hydrophobic paroxysm may be excited by 

 the mention of the name of water, which of course calls up the idea; and a 

 tendency to yawn is in like manner frequently induced by looking at a picture 

 of yawners, or by speaking of the act, or by voluntarily commencing the act, 

 which may then be automatically completed. The automatic performance of 

 actions which were originally voluntary has already been fully discussed ( 749); 

 and we have therefore only to remark here that the fact very strongly supports 

 the view now advanced, as to the singleness of the mechanism which serves as 

 the instrument of both classes of actions, and the essential uniformity of its 

 operation in the two cases. It would be difficult to explain either set of pheno- 

 mena satisfactorily on the hypothesis that there is a "distinct system" of fibres 



