MULTIPLE AND AUTONOMOUS ELECTRICAL RESPONSE 221 



much enhanced. In fact, it appears as if the fundamental 

 excitatory reaction, being now deprived of one of its two 

 modes of expression, exhibited the other with the greater 

 energy. 



We thus see that not only does the electrical response 

 give us a means of detecting the action of external stimulus 

 on a tissue, but that 

 the same mode of 

 indication enables us 

 further to demon- 

 strate the existence 

 of those internal ex- 

 citations which may 

 find mechanical ex- 

 pression in the so- 

 called ' autonomous ' 

 movements. 



One such autono- 

 mous pulsation pre- 

 sent in all plants is 

 that of growth, and 

 by means of the 

 highly magnified re- 

 cord given by the 

 Crescograph. I have 

 shown this to consist 

 of the additive effects 

 of multiple minute 

 pulsatory movements. 

 We see this in fig. 146, 



which gives a series of records of multiple growth responses 

 obtained with the peduncle of Crocus at different times of 

 the day. In the present case, the average period of each 

 pulsation is twenty seconds. In the case of relatively slow 

 pulsations like these, if one electrical connection be made 

 with the growing-point, where such movements are in pro- 

 gress, and the other with an old leaf in which they have 



FIG. 146. Crescographic Record of Multiple 

 Growth -responses in Peduncle of Crocus 



The ordinate represents the extent of responsive 

 elongations in mm. ; the abscissa, time in 

 seconds. 



