XX11 PLANT RESPONSE 



PACl 



Constancy of sum of direct and indirect after-effects — Latent component 

 almost vanishing above the optimum — Variation of receptivity — Direct 

 and indirect response of plant in sub-tonic condition — Table showing 

 direct and indirect effects at different temperatures — Is the change 

 induced by stimulus always of an explosive chemical character ? — Rela- 

 tion between stimulus and response in different tonic conditions— After- 

 effect— Factors which determine periodic after-effects: (i) Stimulus of 

 light — (2) Temperature — (3) Chemical stimulus— (4) Turgidity — Con- 

 tinuous photographic record of the pulsations of Desmodium — Record of 

 periodic variation of rate of growth — Continuous photographic record 

 of periodic variations of transpiration — Continuous photographic record 

 of the variation of the rate of growth — Annual rings and seasonal 

 periodicity ........ ... 456 



CHAPTER XXXV 



AN INVESTIGATION INTO THE DIFFERENT EFFECTS OF DRUGS 

 ON PLANTS OF DIFFERENT 'CONSTITUTIONS' 



General consideration of the problem — * Constitution ' and the elements 

 which determine it — Methods of investigation — Action of carbonic acid 

 gas — Action of ether — Effect of solution of sodium carbonate — Effect of 

 solution of sugar — Effect of alcohol — Effect of acids — Effect of alkali — 

 Antagonistic action of alkalis and acids — Action of strong solution of 

 sodium chloride — Effect of poisonous solution of copper sulphate — 

 Opposite effects of the same dose on different constitutions — Opposite 

 effects of large and small doses . . . . . . . -477 



PART VII.— GEOTROPISM, CHEMOTROPISM, 

 AND GALVANOTROPISM 



CHAPTER XXXVI 



THE RESPONSIVE CURVATURES CAUSED P.Y GRAVITY. 

 NEGATIVE GEOTROPISM 



Statement of the problem of apogeotropic response — Mode in which stimu- 

 lation is brought about : radial-pressure theory, and theory of statoliths 

 — Mechanics of responsive movement — Experiment demonstrating re- 

 sponsive curvature as brought about by unilateral pressure of particles — 

 Record of curvature induced by gravitation — Record of different rates 

 of curvature when specimen is held at angles of 45 and 135 to the 

 vertical — Determination of the true character of apogeotropic response 

 —Responsive curvature of acellular organs — Curvature of grass haulm 

 under gravity — Growth of grass haulm on a klinostat .... 493 



