CHAPTER XV 



POLAR EFFECTS OF FEEBLE AND MODERATE CURRENTS ON 

 VARIOUS SENSITIVE PLANTS 



Polar effects of feeble and moderate currents on (i) leaflets of Mimosa, 

 (2) leaflets oiBiophytum, (3) leaflets of Neptunia, (4) leaflets otAverrhoa 

 carambola, (5) leaflets of Averrhoa hilimhi, and (6) primary leaf of 

 Mimosa — Excitation with feeble current only at kathode-make — 

 Excitation at kathode-make and anode-break, under moderate 

 current — ^Tabular statement of results. 



In the previous chapter I described some typical experi- 

 ments showing the effects of feeble electrical currents on 

 the pulvinus of Mimosa. In order to demonstrate that 

 such effects are universal, it will be necessary to extend this 

 investigation to every kind of motile organ possessing 

 requisitive sensitiveness. I here give a list of the specimens 

 employed. 



First, the leaflets of Mimosa form very sensitive speci- 

 mens, though there are certain experimental difliculties to 

 be overcome. These leaflets are borne on four sub-petioles 

 that radiate from the end of the main petiole. While the 

 excitatory effect is shown in the primary pulvinus by 

 causing the fall of the leaf, the same effect is seen in the 

 pulvinules by the folding of the leaflets upwards. 



Second, the leaflets of Neptunia are moderately sensitive. 

 This plant flourishes in tanks, but can with care be grown 

 in pots. The excitatory effect is exhibited by the folding 

 upwards of the leaflets. 



Third, the leaflets of Biophyttim sensitivum are very 

 sensitive and serve the purpose of the investigations in an 

 admirable manner. These leaflets show excitation by 

 folding downwards. 



