Francis E. Lloyd — 206 — Carnivorous Plants 



trie shock has further permitted the examination of the behaviour of 

 the trap under special conditions of temperature. 



Within the permissible temperature limits (extreme temperatures, 

 it goes without saying, are finally damaging) Czaja found that sensi- 

 tivity increased with higher temperatures, as determined by observa- 

 tion between 15 to 35 deg. C. Raising the temperature gradually to 

 45 deg. was followed by spontaneous closure of nearly all the traps 

 (that is, excepting some of the oldest). Opening again on reduction 

 of temperature to 20 deg. they again closed on gradual lowering to 

 10 deg., the older traps responding in this way on reducing the temper- 

 ature further to 5 deg., all due to the reduction of sensitivity, as shown 

 by appropriate trials (Czaja 1924). 



AsHiDA went further, and found that sudden changes of tempera- 

 ture (he used changes of 10 deg. C.) in either direction would cause 

 closure. From his data the curious fact emerges that sudden reduc- 

 tion of temperature beginning with any workable levels from 10 to 

 40 deg. C, is more effective than sudden rise in temperature at these 

 levels. Further, the higher the initial level of temperature the more 

 sensitive is the trap to rises, and the less sensitive to drops. Exam- 

 ples of stimulation to both rise and fall of temperature are not lacking, 

 e.g. changes in the growth rate of coleop tiles (Silberschmidt), nastic 

 movements of leaves (Stern and Bunning), the curhng of tendrils 

 (MacDougal), cited by Ashida, offer some analogy. Protoplasmic 

 movement is retarded only by a fall in temperature, the Aldrovanda 

 trap being stimulated by both rise and fall, but more by the latter. 

 Aldrovanda appeared therefore to Ashida to be unique in the quantita- 

 tive aspects of behavior in this regard. Metzner (1920) had, however, 

 already shown that bipolar-flagellated Spirillum sp. show a reversal of 

 movement due to thermotaxis both on increase and decrease of tem- 

 perature. But such rises and falls of temperature as can be experi- 

 mentally imposed can scarcely be expected in nature except as slow 

 changes; they can hardly be regarded as affecting appreciably the 

 general economy of the plant. 



In a third paper Ashida has given the results of studies of response 

 of Aldrovanda traps of different ages to weak and strong stimulation 

 applied in the form of constant currents of 30.6 and 70.1 volts. With 

 the strong current all traps of various ages and at different temper- 

 atures (10 to 40 deg.) close promptly in the same time interval. With 

 the weak current, however, the responses were scattered, a frequency 

 polygon expressing the results having its highest node at about the 

 same position as in the case of the strong current stimulation, with 

 secondary nodes scattered to the right of gradually lessening height. 

 The explanation of the delayed responses lies, Ashida beheves, in 

 the distinct and different sensibility of the hairs and the motile zone, 

 diverse excitability of different cells and other possible causes. 



Responses to chemical stimuli. — Both Czaja and Ashida have 

 studied the behavior of Aldrovanda to a series of chemical agents: 

 narcotics, electrolytes (acids, alkalis, salts), non-electrolytes (sugar, 

 glycerine). 



Sugar, glycerine. — It is difficult because of the impenetrable cu- 

 ticle to plasmolyze the cells of the trap unless a cut is made to allow 



