100 HAND-BOOK OF PHYSIOLOGY. 



In addition to the transmission of ordinary sensory and motor im- 

 pulses, the spinal cord is the medium of conduction also of impulses to 

 and from the vaso-motor centre in the medulla oblongata, and probably 

 also contains special vaso-motor centres. 



2. Transference. Examples of the transference of impressions in 

 the cord have been given (p. 84, Vol. II.); and that 'the transference 

 takes place in the cord, and not in the brain, is nearly proved by the fre- 

 quent cases 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 im- 

 pression were in the brain, both should be felt. 



3. Reflection. In man the spinal cord is so much under the control 

 of the higher nerve-centres, that its own individual functions in relation 

 to reflex action are apt to be overlooked; so that the result of injury, by 

 which the cord is cut off completely from the influence of the encephalon, 

 is apt to lessen rather than increase our estimate of its importance and 

 individual endowments. Thus, when the human spinal cord is divided, 

 the lower extremities fall into any position that their weight and the 

 resistance of surrounding objects combine to give them; if the body is 

 irritated, they do not move toward the irritation; and if they are touched, 

 the consequent reflex movements are disorderly and purposeless; all power 

 of voluntary movement is absolutely abolished. In other mammals, e.g. , 

 rabbit or dog, after recovery from the shock of the operation, which takes 

 some time, reflex actions in the parts below will occur after the spinal 

 cord has been divided, a very feeble irritation being followed by extensive 

 and co-ordinate movements. In the case of the frog, however, and many 

 other cold-blooded animals, in which experimental and other injuries of 

 the nerve-tissues are better borne, and in which the lower nerve-centres 

 are less subordinate in their action to the higher, the reflex functions of 

 the cord are still more clearly shown. When, for example, a frog's head 

 is cut off, the limbs remain in or assume a natural position; they resume 

 it when disturbed; and when the abdomen or back is irritated, the feet 

 are moved with the manifest purpose of pushing away the irritation. 

 The main difference in the cold-blooded animals, being that the reflex 

 movements are more definite, complicated, and effective, although less 

 energetic than in the case of mammals. It is as if the mind of the animal 

 were still engaged in the acts; and yet all analogy would lead us to the 

 belief that the spinal cord .of the frog has no different endowment, in 

 kind, from those which belong to the cord of the higher vertebrata: the 

 difference is only in degree. And if this be granted, it may be assumed 

 that, in man and the higher animals, many actions are performed as reflex 

 movements occurring through and by means of the spinal cord, although 

 the latter cannot by itself initiate or even direct them independently. 



Co-ordinate Movement not a proof of Consciousness. The 



