CHAPTER XI 



EFFECT OF ANAESTHETICS, POISONS AND OTHER CHEMICAL 

 REAGENTS ON LONGITUDINAL RESPONSE 



Response modilied l)y physiological change — Carbonic acid causes depression, 

 and transitory exaltation as after-effect— Gradual abolition of response in 

 hydrogen and restoration by access of air— Chemical agents cause contraction 

 or relaxation of plant-tissue — Effect of alcohol causing temporary ex.tltation of 

 response followed by depression and protracted period of recovery — Ether 

 causes relaxation and temporary depression of response — Explanation of 

 anomalous action of ether on stimulated Mimosa leaf — Abolition of response 

 Vjy hydrochloric acid — Response restored by timely application of ammonia — 

 Abolition of response by poisonous reagent — Similarity of effect of chemical 

 agents on the response of animal and vegetable tissues. 



The subject of our inquiry, in this and succeeding chap- 

 ters, will be the determination of those influences which 

 bring about the variation of conductivity and excitability in 

 plant-tissues. The variation of excitability induced in a 

 tissue by chemical reagents, may be studied through the 

 consequent modifications of the responses. Various forms 

 of response which may be used for this investigation are 

 (i) electrical, (2) autonomous, (3) growth, and (4) the simple 

 mechanical response about to be described. A description 

 of the modifications induced in electrical response under the 

 action of chemical reagents will be found on pp. 73-80 of 

 my book, ' Response in the Living and Non-Living.' The 

 effects of chemical reagents on autonomous pulsation and 

 on growth are given in detail in Chapters XXV, XXVII, 

 and XXXV of the present work. But it may be said here, 

 that the results obtained by all these different methods are 

 concordant, and that the simp'e method of mechanical 

 response now to be detailed is to be regarded as an additional 

 corroboration. It should also be borne in mind that the 



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