14 THE BIOLOGY OF THE SEASONS 



But besides seasonal modifications, we have to recognise 

 a possibility which is only beginning to be studied, which 

 adds to the complexity of the biological problem the 

 possibility that external changes may serve as variational 

 stimuli, inducing germinal changes which find expression 

 in the next generation. 



The ingenious zoologist, Professor Semon, has recently 

 propounded a theory which may be noticed in this con- 

 nection. It is called the theory of the " Mneme," and it is 

 based on the fact that when living matter is affected by a 

 stimulus its quality cannot be the same as it was before the 

 stimulus. There is some residual effect, which Semon calls 

 an engram. All stimuli, Semon believes, produce engrams, 

 and the sum of the engrams of a living creature is its 

 " Mneme " its organic reminiscences we may almost say. 

 The " Mneme " may have particular importance in cases 

 where penetrating stimuli, like those of the seasons, recur 

 periodically, revivifying old impressions and re-enforcing 

 them. 



Some biologists believe that this line of thought is 

 useful, and that by following it we may come to understand 

 how the results of experience may be treasured from 

 generation to generation, although individually acquired 

 modifications in the ordinary sense are not entailed. The 

 effects of a stimulus may radiate through the organism, 

 may pass from part to part by nerve paths and proto- 

 plasmic bridges, and may in some cases reach even the 

 germ-cells in their recesses, thus influencing the next 

 generation. This remains a speculation. 



But apart from possibilities of inheritance, it seems to 

 us safe to say that the ceaselessly changing march of the 

 seasons brings to organisms which are agents, not mere 

 pawns in the game new possibilities of creation, of garner- 

 ing experience, of trading with time. 



