3i6 RESEARCHES ON IRRITABILITY OF PLANTS 



longer duration of one minute. The response is now found 

 to consist of a large, followed by two small, pulsations. 



I next took another series of records, with a specimen 

 which had been in a state of standstill for seven hours. 



Fig. 159.— Response of Desmodium leaflet at standstill to stimulus of 

 light of '5 and i minute's duration. 



Stimulus of light was successively applied for one, two, 

 three and four minutes. The general result is somewhat 

 similar to those that have been seen in the previous record. 

 The noticeable differences are, first the diminished amplitude 



Fig. 160. — Response of a depressed specimen of Desmodium to stimulus 

 of light applied successively for one, two, three, and four minutes. 



of response, and the exhibition of decline in the successive 

 responses. The specimen was nearing the critical condition 

 of death, and after a while there was a cessation of all 

 response. In other specimens the critical period was found 



