REFLEX FUNCTION OF THE SPINAL CORD. 501 



constitute the true continuations of the anterior columns of 

 the cord, appears to produce very little paralysis. Disease 

 or division of any part of the cerebro- spinal axis above the 

 seat of decussation is followed, as well-known, by impaired 

 or lost power of motion on the opposite side of the body ; 

 while a like injury inflicted below this part, induces similar 

 paralysis on the corresponding side. 



2. In the second place, the spinal cord as a nerve- 

 centre, or rather as an aggregate of many nervous centres, 

 has the power of communicating impressions in the several 

 ways already mentioned (p. 487). 



Examples of the transference and radiation of impressions 

 in the cord have been given ; and that the transference at 

 least takes place in the cord, and not in the brain, is nearly 

 proved by the case of pain felt in the knee and not in the 

 hip, in diseases of the hip ; of pain felt in the urethra or 

 glans penis, and not in the bladder, in calculus ; for, if 

 both the primary and the secondary or transferred impres- 

 sions were in the brain, both should be always felt. Of 

 radiations of impressions, there are, perhaps, no means 

 of deciding whether they take place in the spinal cord or 

 in the brain ; but the analogy of the cases of transference 

 makes it probable that the communication is, in this also, 

 effected in the cord. 



The power, as a nerve-centre, of communicating im- 

 pressions from sensitive to motor, or, more strictly, from 

 centripetal to centrifugal nerve-fibres, is what is usually 

 discussed as the reflex function of the spinal . cord. Its 

 general mode of action, its general though incomplete 

 independence of consciousness and of the will, and the 

 conditions necessary for its perfection, have been already 

 stated. These points, and the extent to which the power 

 operates in the production of the natural reflex movements 

 of the body, have now to be further illustrated. They 

 will be described in terms adapted to the general rules of 

 reflection of impressions in nervous centres, avoiding all 

 such terms as might seem to imply that the power of the 



