678 THE NERVOUS SYSTEM 



b. Analyze and record the extent of motor paralysis. 



c. Analyze all other disturbances. 



1 1 . Spinal Analgesia. Temporary effects similar to complete section 

 of the cord are produced on injecting cocaine into the spinal canal at the 

 same level. Inject i cc. of 2 per cent, cocaine hydrochlorate into the 

 spinal canal of the twelfth dorsal segment of a dog. Complete analgesia 

 and loss of motor control occur in the hind legs and pelvic parts. This 

 condition passes off in 20 to 40 minutes but is adequate for major surgical 

 operations. 



12. Reflex Reaction Time of Man. Arrange an electric buzzer signal 

 in circuit with a lead off from a sixty cycle alternating current lighting 

 system. The circuit is controlled by a spring key with pin pricking 

 attachment. Use a rapid moving Harvard drum for recording. No 

 time signal is needed, since the buzzer not only records the opening and 

 closing of the key but also the duration of the latent period in K20 

 seconds. Have the reagent close the key quickly with his index ringer. 

 The resulting pinprick will be sufficient stimulus to produce reflex removal 

 of the finger, particularly if he is left in ignorance of the pin. An electric 

 shock can readily be arranged to stimulate the sensory surface only. 



13. Voluntary Reaction Time Conditioned by Simple Choice. Use the 

 signal and recording apparatus arranged as outlined above. For the pin 

 substitute a simple spring key with flag signal device arranged to be used 

 or not at the discretion of the experimentor. The reagent is instructed 

 to close the key and open it instantly provided he sees the flag signal. 

 Read off the reaction time from the buzzer vibrations. Any other sensory 

 channel may be chosen instead of sight. 



In extended experimental work more and more complicated nerve 

 reactions should be measured. 



