RELATION BETWEEN PLANTS AND LIGHT. 373 



fruits of the orchard need to be ripened by the 

 agency of heat; and at that season the heat- 

 rays are most predominant. It appears, indeed, 

 that even during the day, the relative force of 

 the three principles in the solar ray is modified. 

 .In the evening there is less actinic force than 

 in the morning; and at noon there is more 

 luminous and calorific power. All these re- 

 sults are of deep interest, and are entirely of 

 recent discovery. What wisdom is manifest in 

 this long unsuspected but marvellous arrange- 

 ment of vegetable functions and light ! What 

 views does it give us of the strict dependence 

 of one part of this fair creation upon the 

 other, and of the manner in which various 

 phenomena have been linked in such close 

 union by the Divine Creator ! He only is as 

 excellent in working, as He is Almighty in 

 power ! 



From these considerations we may learn, 

 first, the importance of light to the vegetable 

 world; and, secondly, the importance of light 

 in order to the preservation of the purity of 

 the atmosphere. Without light, no plant could 

 long exist ; without light, little carbonic acid 

 could be decomposed ; and the air would be so 

 much vitiated, as to become irrespirable to the 

 animal world. In how many ways is this cheer- 

 ful sun-light connected, directly and otherwise. 



