10 president's address. 



phenomena of movement or those of structure. If this is allowable — 

 and the weight of evidence is strongly in its favour — a conclusion of 

 some interest follows. 



If we reconsider what I have called the indirectness of stimulation, we 

 shall see that it has a wider bearing than is at first obvious. The ' internal 

 condition ' or ' physiological state ' is a factor in the regulation of the 

 organism's action, and it is a factor which owes its ciiaracter to external 

 agencies which may no longer exist. 



The fact that stimuli are not momentary in effect but leave a trace of 

 themselves on the organism is in fact the physical basis of the phenomena 

 grouped under memory in its widest sense as indicating that action is 

 regulated by past experience. Jennings ^ remarks : ' In the higher 

 animals, and especially in man, the essential features in behaviour depend 

 very largely on the history of the individual ; in other words, upon the 

 present physiological condition of the individual, as determined by the 

 stimuli it has received and the reactions it has performed. But in this 

 respect the higher animals do not differ in principle, but only in degree, 

 from the loM'er organisms. . . .' I venture to believe that this is true 

 of plants as well as of animals, and that it is further broadly true not 

 only of physiological behaviour, but of the changes that are classed as 

 morphological. 



Semon in his interesting book. Die Mneme,^ has used the word 

 Engram for the trace or record of a stimulus left on the organism. In 

 this sense we may say that the internal conditions of Pfeffer, the 

 physiological states of Jennings, and the internal conditions of Klebs 

 are, broadly speaking, Engrains. The authors of these theories may 

 perhaps object to this sweeping statement, but I venture to think it is 

 broadly true. 



The fact that in some cases we recognise the chemical or physical 

 character of the internal conditions does not by any means prevent our 

 ascribing a mnemic memory-like character to them, since they remain 

 causal agencies built up by external conditions which have, or may have, 

 ceased to exist. Memory will be none the less memory when we know 

 something of the chemistry and physics of its neural concomitant. 



fall into line witla what we know of the regulation of actions in the higher organisms. 

 Pfeffer {Physiology of Plants, Eng. trans., iii. 10) has briefly discussed the possibility 

 of thus considering the nucleus as a reflex centre, and has pointed out difficulties in 

 the way of accepting such a view as universally holding good. Delage {L'Hereditc, 

 2nd edit., 1903, p. 88) gives a good summary of the evidence which induces him 

 to deny the mastery of the cell by the nucleus. Driesch, however (Anahjtische 

 Theorie der organischen EntwieUung , 1894, p. 81), gives reasons for believing that 

 the cjtoplasm is the receptive region, while the nucleus is responsible for the 

 reaction, and it is on this that he bases his earlier theory of ontogeny. 



' P. 121 (1901). 



^ Die Miieme, ah erhaltendes Priiizij) im ^\^ecJlSl'l des organischen Oeschehens, 

 von Kichard Semou, 1" Auflage, Leipzig 1904, 2" Auflage, 1908. It is a pleasure 

 to express my indebtedness to this work, as well as for the suggestions and criticisms 

 which I owe to Professor Semon personally, 



