THE SPINAL CORD AND REFLEX ACTIONS. 607 



common example is the well-known trick of pinching the 

 nose or upper lip to prevent a sneeeze. The whole question 

 of reflex inhibition is at present very obscure. It may be due 

 to the excitation of special fibres which inhibit reflex centres, 

 as the fibres of the depressor nerve do the activity of the vaso- 

 constrictor centre ; or to tlie fact that one nerve impulse in 

 the cord in some cases blocks or interferes with another; or 

 partly to both. 



Psychical Activities of the Cord. Since we can get quite 

 marked reflex movements in the lower part of the Body of a 

 man whose cord is divided and who cannot voluntarily move 

 his lower limbs, and on questioning him find that he feels 

 nothing and is quite ignorant of his movements unless he sees 

 his legs, it is most probable that the spinal cord in all cases is 

 devoid of centres of consciousness and volition: this is not 

 certain, however; for there might well be a less division of 

 physiological labor between the cord and brain of a frog, than 

 between those of a man. Still we are entitled to good evi- 

 dence before we admit that things so similar as the human 

 cord and that of the frog possesses different properties. Co- 

 ordinated movements following a given stimulus, or cries 

 emitted by an animal, will not suffice to prove that it is con- 

 scious, since we know these may occur entirely unconsciously 

 in men, who alone can tell us of their feelings. We must 

 look for something that resembles actions only done by men 

 consciously. In the frog it has been maintained that we have 

 evidence of such. If a bit of 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 can- 

 not 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 con- 

 scious and voluntary employment of new procedures under 

 unusual circumstances. Bat a close observation of the phe- 

 nomenon shows that it ,/ill hardly bear this interpretation; 

 the movements of the other leg are very irregular and inco- 

 ordinate, and much resemble reflex convulsions stirred up by 

 the prolonged 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 



