The Light Relation 



419 



lished that injury may result from continuous or lengthy 

 exposure to intense light. Many of the simpler green algse 

 may be killed by an exposure to brilliant sunlight of less 



FIG. 114. Effect of light upon a plate culture of Pseudomonas campes- 

 tris; colonies have appeared only where the plate was protected by a 

 letter (W) screen. [After Russell and Harding.] 



than one hour. It has been shown conclusively that strong 

 light inhibits the action of various enzymes. The diastases 

 are notably affected, so that the conversion of starch in a 



