4 PRESIDENTS ADDRESS. 



made known to the world in the words of Mr. Darwin and Mr. Wallace. 

 This would be a gigantic task, for which I am quite unfitted. It seems 

 to me, moreover, that the first duty of your President is to speak on 

 matters to which his own researches have contributed. My work — such 

 as it is — deals with the movements of plants, and it is with this subject 

 that I shall begin. I want to give you a general idea of how the changes 

 going on in the environment act as stimuli and compel plants to execute 

 certain movements. Then I shall show that what is true of those tem- 

 porary changes of shape we describe as movements is also true of the 

 permanent alterations known as morphological. 



I shall insist that, if the study of movement includes the problem of 

 stimulus and reaction, morphological change must be investigated from 

 the same point of view. In fact, that these two departments of inquiry 

 must be classed together, and this, as we shall see, has some important 

 results — namely, that the dim beginnings of habit or unconscious memory 

 that we find in the movements of plants and animals must find a place 

 in morphology ; and inasmuch as a striking instance of correlated mor- 

 phological changes is to be found in the development of the adult from 

 the ovum, I shall take this ontogenetic series and attempt to show you 

 that here also something equivalent to memory or habit reigns. 



Many attempts have been made to connect in this way the phenomena 

 of memo?'y and inheritance, and I shall ask you to listen to one more 

 such attempt, even though I am forced to appear as a champion of what 

 some of you consider a lost cause — the doctrine of the inheritance of 

 acquired characters. 



Movement. 



In his book on 'The Power of Movement in Plants' (1880)' my 

 father wrote that ' it is impossible not to be struck with the resemblance 

 between the foregoing movements of plants and many of the actions 

 performed unconsciously by the lower animals.' In the previous year 

 Sachs - had in like manner called attention to the essential resemblance 

 between the irritability of plants and animals. I give these statements 

 first because of their simplicity and directness ; but it must not be for- 

 gotten that before this Pfeffer^ had begun to lay down the principles 

 of what is now known as Reizphysiologie, or the physiology of stimulus, 

 for which he and his pupils have done so much. 



The words of Darwin which I have quoted afibrd an example of the 

 way in which science returns to the obvious. Here we find revived, in a 

 rational form, the point of view of the child or of the writer of fairy 

 stories. We do not go so far as the child ; we know that flowers do not 

 talk or walk; but the fact that plants must be classed with animals as 

 I'ftwards their manner of reaction to stimuli has now become almost a 



> p. 571. " Arheiten, ii. 1879, i). 282. 



s Osmntisclw rnter.nichwngen, 1877, p. 202. 



