232 RESEARCHES ON IRRITABILITY OF PLANTS 



I next give a table showing results obtained with 

 moderate current : — 



Table XV. — Effect of Moderate Current on Various Specimens 

 of Sensitive Plants 



Type II. — Excitation formula Km Ab 



It is here shown that we have examined not one species 

 only but all the species that were available for experiment. 

 More than a hundred experiments have moreover been 

 carried out on different specimens. The result of all these 

 investigations has been to demonstrate clearly the fact that 

 in plants, under a feeble current, it is the kathode alone that 

 excites at make, while under a moderate current excitation 

 takes place by the make of kathode and the break of anode. 



Thus, so far from there being any necessary divergence in 

 the excitatory polar reactions of fibrillated and unfibrillated 

 protoplasm, we find on the contrary that they are identical 

 in the plant and in the animal. In other words, the respon- 

 sive characteristics of Type I. and Type II. in plants corre- 

 spond in every respect to those in animal tissues which are 

 classed under Pfluger's Law as Stage I. and Stage II. 



This is not by any means to be taken as a complete 

 statement of the law of polar effects. We shall find that 

 if the current be increased still further, certain new types 

 of effects make their appearance which will be described in 

 detail in a subsequent chapter. In the meantime I have to 

 describe certain further characteristics of these polar effects 



