SUN-LIGHT AND PLANTS. 369 



the rays of the sun exert a most important 

 influence upon the vegetable kingdom. Per- 

 haps there are few more pleasing subjects 

 in the chemistry of creation than that of the 

 influence of light upon plants. The whole of 

 the three principles resident in the sunbeam, 

 namely, the luminous, actinic, and calorific rays, 

 produce highly interesting effects upon plants, 

 and are, together, strictly necessary to the 

 health, development, and perfection of the 

 vegetable being. Let us briefly advert to the 

 facts now known upon this subject. It has al- 

 ready been stated, that, at the commencement of 

 vegetable 'life, the actinic or chemical rays have 

 been found to be indispensably necessary for the 

 Commencement of the process of germination. 

 So soon as this process is ended, the plant having 

 now raised its tender head into the light, it 

 enters into a new connexion with the air, and 

 with the sunbeam. During germination the 

 seed absorbed oxygen from the air, under the 

 influence of the powers of vital chemistry and 

 actinism combined. But when the first ray of 

 unshaded sun-light falls upon the young leaf, its 

 processes undergo an entire change. It now 

 becomes green, in consequence of the action of 

 the rays of light upon some of the ingredients 

 present in the leaves. And now, almost to the 

 end of its existence, it pours out oxygen gas all 



2 B 



