BLUE GRASS. 137 



days the vigorous plants from the ■uncolored bell 

 glass were moved to the green. In eight days 

 they had become less sensitive; in two more the 

 sensitiveness had almost entirely disappeared, and 

 in another week they were all dead. Green rays of 

 light appear to have no more influence on vegeta- 

 tion than complete absence of light; and Mr. Best 

 believes, adds the Academy, that the sensitive 

 plant exhibits only the same phenomenon as all 

 plants colored green, but to an excessive degree." 

 It is thus seen that blue light, green light and 

 darkness are all injurious when long continued. 

 We know that many plants will grow in partial 

 shade, and that some will thrive better if somewhat 

 shaded. The experiments on colored glass taken 

 together fail to show that blue glass is of any other 

 advantage than as a shade, and that glass of any 

 other color, except yellow, will serve the same 

 purpose. 



