2Q4 RESEARCHES ON IRRITABILITY OF PLANTS 



secured in the pulsating movement of the cut specimens, 

 I reproduce here a continuous record lasting for four hours 

 (fig. 142), the movements themselves being maintained 

 uniform for more than seven hours. The run of the breadth 

 of the plate was accomplished in one hour and twenty 

 minutes, successive series of records being taken on the 

 same plate from below to above. It will be seen how 

 uniform are the successive pulsations, not only as regards 



Fig. 142. — Continuous record of pulsations of Desmodium leaflet 

 for four hours ; the series to be read from below to above. 



the amplitude, but also the period. It is only after securing 

 such uniformity, under normal standard conditions, that 

 the experimenter is justified in drawing correct inferences, 

 from variations induced in the record, on the influence of 

 changed conditions which he has introduced. 



Time-Relations of the Pulsating Movements of 



Desmodium Leaflet 

 The up-and-down movement of the Desmodium leaflet 

 is characterised by certain peculiarities. In its usual form 



