78 CEREBRAL FORCES. [i. 



pression. We infer it to be in the motor nerves from the 

 actions which the cerebral impressions of conceptions produce 

 in those structures to which these nerves are distributed, and 

 because compression of the nerve prevents the transmission of 

 internal impressions to the mechanical machines. As to the 

 sensitive nerves which simply feel, and manifest no visible 

 movements from either kind of impression, we know that the 

 cerebral impression is in them by its operations, which, although 

 certainly taking place, are not visible. 



146. The cerebral conceptional impression causes, at the 

 origin of each nerve on which it duly acts, a movement (of the 

 vital spirits) from above downwards towards the terminating 

 fibrils which feel (122). It is at this, the extremest point of the 

 nerves, that this movement is either wholly reflected, or ceases 

 (126); for from that point the external impression causes an 

 opposite movement towards the brain. Further observation 

 may enable us to determine something as to this change, as for 

 example, when a strong sensational conception acts on the 

 nerve with unusual vigour. 



147. When the terminations of the nerves are carefully 

 observed in powerful sensational foreseeings, particularly in the 

 instincts or passions, it is obvious that they are erected, and 

 become more prominent. Thus the papillae of the tongue, in 

 which the gustatory nerves terminate, are visibly elevated when 

 the expectation or desire to taste a piece of sugar or salt is 

 excited by bringing it near to the tongue. So also the nerve- 

 points in the fingers are evidently elevated, when one attempts 

 to feel something more distinctly, which is the foreseeing in a 

 desire. " The sensitive points of the fingers,^^ Haller remarks, 

 '^ are slightly elevated during an act of attention (an expecta- 

 tion), just as we see in rigors, in the nipple of the mamma, and 

 in a portion of bowel hanging out of the abdomen.^^ {' Phys.,^ 

 §431.) Probably shivering ought to be classed with the sen- 

 tient actions produced through the nerves in the mechanical 

 machines. That the sensitive points in the nipple are elevated 

 by the expectation of an act of suckling, or simply by titillation, 

 is quite certain. With regard to the senses of feeling and taste 

 many similar observations have been made, but not with regard 

 to the other senses. This erection of the nerve-points is there- 

 fore a true sentient action. 



