THE SHASTA DAISY 



remote than the time at which the European and 

 American daisies were separated. 



The Plant as a Camera 



To make the meaning of this quite clear, we 

 must recall that a given organism — say in this 

 case a given stock of daisies — is at all times 

 subject to the unceasing influence of the conditions 

 of life in the midst of which it exists. The whole 

 series of influences which we describe as the 

 environment is perpetually stamping its imprint 

 on the organism somewhat as the vibrations of 

 light stamp their influence on a photographic 

 plate. 



Indeed, as I conceive it, the plant is in effect a 

 photographic plate which is constantly receiving 

 impressions from the environing world. 



And the traits and tendencies of the plant that 

 are developed in response to these impinging 

 forces of the environment are further comparable 

 to the image of the photographic plate in that 

 they have a greater or less degree of permanency 

 according to the length of time during which they 

 were exposed to the image-forming conditions. 



If you expose a photographic plate in a 

 moderately dim light, let us say, for the thou- 

 sandth part of a second, you secure only a very 

 thin and vague negative. But if without shifting 

 the scene or the focus of the camera, you repeat 



[23] 



