REFLEX ACTION OF THE SPINAL COED. 311 



mals, especially frogs, are applicable to the human subject, 

 and to indicate the muscular actions which depend upon the 

 cord as a nerve-centre. 



It is only necessary, after what has gone before, to indi- 

 cate in a general way the phenomena observed in the human 

 subject which illustrate the reflex action of the cord. It is a 

 common observation, in cases of paraplegia in which the 

 lower portion of the cord is intact, that movements of the 

 limbs follow titillation of the soles of the feet, these move- 

 ments taking place independently of the consciousness or the 

 will of the subject experimented upon. Acephalous foetuses 

 will present reflex movements, movements of respiration, 

 and will even suck when the finger is introduced into the 

 mouth. Observations of this kind are so numerous and fa- 

 miliar, that they need not be cited in detail. Experiments 

 have also been made upon criminals after decapitation ; and 

 although the reflex phenomena are not so well marked and 

 cannot be excited so long after death as in cold-blooded ani- 

 mals, they are sufficiently distinct. In 1869, quite an elab- 

 orate series of investigations of this kind was made by Ro- 

 bin. 1 



It is difficult, in studying, in the human subject, the ordi- 

 nary phenomena of movements in the voluntary muscular 

 system, to isolate the reflex phenomena from those acts in- 

 volving sensation and volition. In many persons, titillation 

 of the soles of the feet produces violent contractions of 

 muscles, which cannot be arrested by an effort of the will, 

 and this may even be followed by general convulsions. 

 When we unexpectedly touch an irritating surface with the 

 hand, the muscles of the arm act so quickly, that we may 

 suppose that this takes place before we really appreciate the 

 painful sensation ; and, if the impression be very severe, we 

 may have movements more or less general. Operating upon 

 highly-sensitive parts, it is frequently impossible to arrest re- 



1 ROBIN, Observations anatomiques et physiologiques faites sur des suppli- 

 cies par decollation, Journal de Vanatomie^ Paris, 1869, tome vi., p. 69, et seq. 



