ECONOMY OF THE NERVOUS SYSTEM. 481 



nance of phenomena of this latter class. They are 

 manifested, however, in various ways even in the 

 higher animals ; for if a limb be separated from 

 the body, its muscles can, for a considerable time 

 after the separation, be excited to contraction by 

 irritations of a mechanical, chemical, or elec- 

 trical kind, applied to the nerves which are sent to 

 those muscles. Similar phenomena occur if the 

 same irritations be applied to that part of the spinal 

 cord whence those nerves arise ; and they take 

 place equally if the head has been previously re- 

 moved, or if that portion of the spine be separated 

 from the rest by a complete division of the column 

 both above and below that part. In this latter case, 

 a still more remarkable phenomenon may be ob- 

 served, namely, that irritation of the remote parts 

 of other nerves, which have an afferent function, is 

 followed by the same muscular movements, pro- 

 vided the connexions of these nerves with the same 

 part of the spinal cord as that from which the 

 motor nerves proceed, has been preserved. The 

 movements thus excited are often the very same in 

 kind as those which in the living and sentient ani- 

 mal would result from sensation and volition ; yet 

 we are quite certain that no consciousness can 

 attend them. If, for, example, the hind part of the 

 body of a frog be separated from the rest, and the 

 sole of the foot be pricked, the limb is suddenly 

 retracted, with the same gesture as it would have 

 been during life, and of course, with the same 

 apparent indication of suffering :* but this appear- 

 ance is deceptive, for the impression was received 



* Mayo's Outlines of Human Pliysioloofy, p. 231. 

 VOL. II. I I 



