210 



COMPARATIVE ELECTRO-PHYSIOLOGY 



In the cases mentioned, this was derived from impinging 

 stimulus. The internal energy of a tissue may, however, be 



FIG. 138. Multiple Electrical Responses under Different Forms of 

 Stimulus in Different Organs 



(a) In Mimosa due to thermal, and (t>) to chemical stimulation ; (c) in 

 peduncle of Biophytum, due to thermal stimulus ; [N.B. This series 

 persisted for two hours.] (d) in hypocotyl of Tamarindus indica, due 

 to stimulus of cut. 



increased, and multiple response may consequently be 

 initiated in other ways, as, for instance, by adequately raising 



the temperature of the plant. 

 This is seen in the following 

 record of pulsatory responses as 

 induced in a young leaflet of 

 Biophytum, when the temperature 

 was raised to 35 C. With the 

 increase of internal energy, the 

 turgidity of the tissue was en- 

 hanced, and the excessive hydro- 

 static tension thus brought about 

 induced autonomous pulsations 

 (fig. 140), as in a quiescent snail's 

 heart similar pulsations are in- 

 duced by increase of the internal 

 hydrostatic pressure. I have else- 

 sponse to Single Thermal where shown that the energy 



Shock in Frog's Stomach . 



which expresses itself in pulsatory 



movements may be derived by the plant, either directly from 

 immediate external sources ; or from an excess of such 



