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lar organ of some ordinary plant, say the peduncle of daffodil, it 

 is clear that the protected inner side of the tube must be the 

 more excitable. When this is cut into the form of a spiral strip, 

 and excited by means of an electrical shock, we observe a re- 

 sponsive movement to take place by curling, due to the greater 

 contraction of the inside of the strip. This mechanical response 

 is at its maximum at that season which is optimum for the plant. 

 When the plant is killed, its response disappears. 



In Mimosa, under continuous stimulation, there is a fatigue- 

 reversal, the responsive fall being converted into a movement of 

 erection. The same thing happens in the response of ordinary 

 plants, when the first contractile movement of the spiral, for in- 

 stance, is reversed, under continuous stimulation, to an expansive 

 uncurling. 



An important series of observations is that on the modification 

 of response by the tonic condition of the tissue. When the con- 

 dition is sub-tonic, response is by the abnormal positive, instead 

 of the normal negative, reaction. A strong or long-continued 

 application of stimulus, however, converts this abnormal positive 

 into normal negative. 



Another important phenomenon is that for which the name of 

 multiple response has been suggested. When the stimulus is 

 very strong, the response is often not single, but repeated, or 

 multiple. Excess of stimulus is thus seen to remain latent in 

 the tissue, for rhythmic expression later. This storage of en- 

 ergy from the environment may in some cases be so great as to 

 cause the continuance of rhythmic activity, even in the absence 

 of immediate stimulation. We thus obtain a natural transition 

 into so-called spontaneous or autonomous movements. 



The various peculiarities of the spontaneous movements ex- 

 hibited by Desmodium gyraus, or the telegraph plant, may be 

 studied in the automatic record taken by the optical lever. The 

 rhythmic tissues of the plant are then found to have character- 

 istics which correspond to those of similar tissues in the animal. 

 Lowering of temperature enhances the amplitude and diminishes 

 the frequency of pulsation in the rhythmic cardiac tissue of the 

 animal. The same is found to be true of the pulsatory activity of 



