600 Dynamic Theory. 



rectum and bladder being likewise out of reach of the voluntary gan- 

 glionic centers, their movements were subject only to the unrestrained 

 stimulation which their contents naturally cause, and their evacuations 

 were uncontrolled by the will, and accompanied by violent convulsions 

 and spasmodic contractions of the organs. Another case is cited in 

 which the in j ury was higher up, namely, at the lower part of the neck. 

 The patient at first had no control of the lower limbs, trunk or hands, 

 but a slight control of the wrists, a little more of the elbows, and still 

 more of the shoulders, and there was a great reduction of the sensibil- 

 ity of the hands and feet. At first, tickling one sole caused reflex move- 

 ment in that limb only ; later, as recovery progressed, tickling one sole 

 produced movements in both legs, and still later, on the 26th day af- 

 ter the hurt, such single stimulus caused movements not only in both 

 legs but in the muscles of the trunk and arms as well. When the pa- 

 tient began to recover voluntary power over his muscles, so as to put 

 his feet to the floor, the stimulation of their soles, caused by their con- 

 tact with the floor, would instantly cause the bending of the knees. ' 'On 

 the 95th daj r this effect did not take place till the patient had made a 

 few steps ; the legs then had a tendency to bend up, a movement which 

 he counteracted by rubbing the surface of the belly ; this rubbing ex- 

 cited the extensor muscles to action, and the legs became extended with 

 a jerk. A few more steps were then made, the maneuver was repeated, 

 and so on." Recovery finally took place in both these cases. (Carpen- 

 ter's Physiology. ) 



The action of the spinal cord when disconnected from the brain, is 

 the same in the lower animals as in man, as has been shown by numer- 

 ous experiments. If the proper part of the sensitive skin be excited, 

 the stimulus is instantly reflected back to the limbs, causing their con- 

 traction. In experiments with a Salamander, in which the spinal cord 

 had been cut in two, when the feet were irritated, especially by heat, 

 convulsive movements were set up in the legs and tail. Yet it Tvas 

 proved that the animal possessed no sensibility, because the trunks of 

 the same afferent nerves might be severed by cutting off the leg of the 

 animal without causing it to wince or show any of the signs of pain that 

 it would have shown had the connection of the spinal cord with the 

 brain been undisturbed. 



It is not to be supposed that the movements of the muscles are 

 caused by the stimuli acting direct^ without the jnedium of the nerves, 

 for if the nerve trunks are cut between their sensitive ends in the skin, 

 and their connection with the spinal cord, no movements follow the 

 stimulation. It is thus shown that the movement of the stimulus is ac- 

 tually up the afferent trunk to its junction with the spinal cord, and 

 thence down by the efferent trunk to the muscles of the limbs. It has 



