xxii PLANT RESPONSE 



PACE 



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 

 peiiodic 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, CITEMOTROPISM, 

 AND GALVANOTROPISM 



CHAPTER XXXVI 



THE RESPONSIVE CURVATURES CAUSED BY 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 <>f acellular organs— Curvature of grass haulm 

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



