DIFFERENT TYPES OF RESPONSE 



127 



will be shown later, by the sum total of energy latent in 

 the tissue. From the curve of response given in fig. 6j, it 

 will be seen that at the beginning of the experiment, the 

 length of the tendril being constant, the first part of the 

 record was horizontal, instead of descending, as would have 

 been the case had the tendril been growing. The con- 

 tractile shortening brought about by stimulus is here 

 represented upwards. The stimulus of induction shock 

 was now applied at intervals of one minute, and the 

 record shows that the recovery, instead of stopping short at 

 the level of the horizontal line, has proceeded beneath, 

 thus indicating that stimulus has been effective not only 

 in producing contractile response, but also in afterwards 

 initiating growth! (Cf. fig. 178.) 

 And further, as the stimulus 

 goes on causing not only 

 mechanical response, but also 

 accelerated growth, we see that 

 the successive mechanical re- 

 sponses are undergoing dimi- 

 nution. The application of 

 stimulus ceased at the end of 

 the fourth response, and we 

 observe active growth proceed- 

 ing from this point as a result 

 of the energy absorbed from 

 the previous stimuli. We have 

 thus demonstrated the very 

 curious case in which the build- 

 ing up process is attended by an actual diminution of re- 

 sponse, and where, after stimulation, the energy of the 

 responding organ, instead of being reduced, is raised above 

 par. This experiment explains why an athlete in constant 

 practice does not waste away, but actually increases, muscle. 



Fig. 67. Mechanical Response 

 shown upwards in Tendril of 

 Passiflora in which Growth was 

 originally at Standstill 



Stimulation, besides producing 

 mechanical response, initiated 

 the opposite movement of 

 growth, as shown by the slope 

 of the base-line downwards. 



