PSYCHICAL ACTIVITIES OF THE SPINAL COED. 583 



acidulated paper be put on the thigh of a decapitated frog, 

 the animal will bend its knee and use its leg to brush off the 

 irritant; always using this same leg if the stimulus be not 

 so strong as to produce disorderly reflexes. If now the 

 foot be tied down so that the frog cannot raise it, after a 

 few ineffectual efforts it will move the other leg, and may 

 wipe the paper off with it. This it has been said shows a 

 true psychical activity in the cord; a conscious and volun- 

 tary employment of new procedures under unusual circum- 

 stances. But a close observation of the phenomenon shows 

 that it will hardly bear this interpretation; the movements 

 of the other leg are very irregular and inco-ordinate, and 

 rnugh resemble reflex convulsions stirred up by the pro- 

 longed action of the acid, which goes on stimulating the 

 skin nerves more and more powerfully. Even if new 

 muscles came, in an orderly way, into play under the 

 stronger stimulus, that would not prove a volitional con- 

 scious use of them; we see quite similar phenomena when 

 there is nothing purpose-like in the movement. Many 

 dogs reflexly kick violently the hind leg of the same 

 side when one flank is tickled. If this leg be held and 

 the tickling continued, very frequently the opposite hind 

 leg will take on the movements, which it never does in 

 ordinary circumstances. This is quite comparable to the 

 frog's use of its other leg under the circumstances above 

 described, but here it would be obviously absurd to talk of 

 a volitional source for such a senseless movement. 



Putting together, then, the testimony of persons with 

 injured spinal cords, and the observations made on them 

 and on animals, we may tolerably safely conclude that the 

 cord contains no centres of consciousness. There are, how- 

 ever, persons who maintain that in such cases the cord itself 

 feels though the individual does not, whatever that may 

 mean; if the statement is used merely to imply that the 

 cord is irritable (just as a muscle is) no one denies it; but 

 it is an unnecessarily confusing method of stating the fact. 



The Cord as a Transmitter of Nervous Impulses. In 

 the gray substance, as we have seen, there is reason to 

 believe that nervous impulses can pass in all directions, 



