PLANT RESPONSE 135 



worked out in considerable detail, and the result is wholly 

 confirmatory, in variously modified as well as in normal 

 conditions, such as temperature, drugs or poisons. So 

 exact is the correspondence that a poison which stops 

 the heart in its phase of contraction also stops Desmodium 

 in its contracted phase, while the poison which stops the 

 heart in relaxation does the same for the plant. And 

 while for the heart it has been known that one poison 

 may be used as the antidote to the other, so it turns out 

 with the poisoning of Desmodium. 



Yet another point of interest appears. The actively 

 rhythmic muscle of the heart is more resistant to ex- 

 ternal stimulus than is ordinary muscle : e.g. it resists 

 tetanisation by external electric shock. Similarly for the 

 active Desmodium leaflet. Thus that passive yielding 

 of the organism or organ to external stimuli, of which 

 we have so often seen cases above, has here its limit : 

 and we see the internal energy of the organism now, as it 

 were, vindicating itself against interferences from the out- 

 side environment. We may thus still speak of ' automatic 

 movements/ and concede a certain independence to the 

 organism, and individuality to the organ. 



The general thesis that plant and animal physiology 

 despite all differences of aspect and habit of life, and of 

 organisms in detail are yet profoundly analogous is again 

 strikingly confirmed. 



Turning next to the section on Growth, our knowledge 

 is greatly advanced, as will be found in greater detail 

 in a subsequent chapter. It is, however, enough here 

 to note that for the vegetable physiologist the most 

 interesting of all these new conceptions may lie in 

 the reinterpretation of the growth-process, as itself 

 a phenomenon of automatism, comparable to that 

 of Desmodium pulsation. For here we have the 

 rhythmic activity controlled by inner stimuli, which 

 present a certain autonomy of their own, and yet are also 

 dependent for their continuance upon energies ultimately 



