276 RESEARCHES ON IRRITABILITY OF PLANTS 



of Pfluger's Law. Against their views is brought the fact that 

 in the unfibrillated protoplasm of Protozoa the reactions 

 observed are more or less opposed to those of Pfluger's 

 generalisation. 



Next are those who hold with Verworn that, in view of 

 the anomalous reactions of unfibrillated protoplasm in 

 Protozoa, there could not possibly be any law of polar reactions 

 of universal applicability. 



There is, however, a third view still possible. I have 

 shown that the reactions of fibrillated and unfibrillated 

 protoplasm are not necessarily opposed, since the plant, 

 within certain limiting values of current, shows reactions 

 identical with those which are normal in animal tissues. 



If then we find that the generally recognised reactions 

 of stage I. — namely, response at kathode-make only — can 

 be transformed into those of stage II. — response at kathode- 

 make and anode-break — by merely increasing the intensity 

 of current, then there can be no inherent impossibility in 

 further transformations into Types III. and IV. under still 

 further increase of the current-intensity. 



The possibility of such transformations has now I think 

 been demonstrated by the experiments described in this and 

 previous chapters on numerous species of sensitive plants. 

 It has also been shown, further, that these polar reactions 

 were subject to variation under physiological modification 

 of the tissues. And finally, in plants whose reactions were 

 already established as identical with those of animal tissues, 

 it has been shown that — under the separate or joint action 

 of an increasing current and physiological modification — 

 responses could be obtained which were similar to the 

 so-called anomalous responses characteristic of Protozoa. 



Summary 



The after-effect of moderate stimulation converts the 

 polar reaction of a given type to one of higher type. 



Under the same exciting current the resulting type of 



