XXVIII.— ON THERMONASTIC PHENOMENA 



Bij 



Sir J. C. BoSE, 



Af^aisted hy 



SURENDRA Chandra Das. 



In describing thermonastic curvatures Pfeffer says that 

 " a special power of thermonastic response has been 

 developed by various flowers, in which low temperatures 

 produce closing movements, and high temperatures, open- 

 ing ones. The flowers of Crucus vermis and Crocus Inteus 

 are specially responsive, as also those of Tulipci Gesner- 

 iana for these flowers perceptibly respond to a change of 

 tepmerature of half a degree centigrade. '** 



We have hitherto studied the response of various organs 

 to stimulus ; we have now to deal with the effect of 

 thermal variation. Does rise of temperature act like other 

 forms of stimuli or is its action different ? We have 

 therefore to find : 



(1) The physiological effect of variation of temperature. 



(2) Whether thermonastic irritability is confined only 



to certain classes of organs, or is it a pheno- 

 menon of very wide occurrence ? 



(3) Whether variation of temperature induces in aniso- 



tropic organs only one type of response, or two 

 types, positive and negative. 



• Pfeffer— 76!t/, Vol. Ill, p. 112. 



