362 



GENERAL PHYSIOLOGY 



while the stimulus was passing over a piece of nerve 3 cm. in 

 length. It is thus found that the rate of conduction of the 



FIG. 154. Du Bois-Reymond's spring-myograph. 



stimulus in a frog's nerve under normal conditions amounts to 

 approximately 26 m. in the second. 



Other forms of living substance conduct the reaction considerably 

 more slowly and some to a very short distanee only, the effect 

 being gradually extinguished with the distance. In very slowly 

 conducting objects the rate of conduction can be followed with the 



FIG. 155. Ascending limb of the myographic curve taken with the spring-myograph. R, Moment 

 of stimulation ; 1, beginning of the contraction upon stimulation of the nerve at a remote 

 place (Fig. 153) ; 2, beginning of the contraction upon stimulation immediately at the 

 muscle. Below, the curve of the tuning fork. 



eye. Thus, in Difflugia the rate of conduction of the ex- 

 citation can be very easily recognised under the microscope in the 





